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COPYRIGHT DEPOSITS 



PRINCIPLES 



OF 



PLANT CULTURE 

AN ELEMENTARY TRKATISE DESIGNED AS 
A TEXT-BOOK FOR BEGINNERS IN AG- 
RICULTURE AND HORTICULTURE 



BY 

E. S. G O F F 

PROFESSOR OF HORTICULTURE IN THE UNIVERSITY OF WISCONSIN 



THIRD REVISED EDITION 



UNIVERSITY CO-OPERATIVE CO. 

MADISON, WISCONSIN 

19 6 



av 



LIBRARY of CONGRESS 
Two Copies Received 

JAN 6 t906 

^ Copyriifht Entry 
/ fLASS 6C XXc. Ho. 






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Copyright, 1897 
By E. S. G O F F 



Copyright 1906 
By C. F. C R O N K 

Administrator Goff Estate 



Cantwell Printing Company 
madison, wisconsin 



PREFACE 

This book has groWii. o-^b-of the- author 's experience 
in the lecture room and laboratory, while giving in- 
structions to students in the Short Course in Agricul- 
ture, in the University of Wisconsin. 

It is intended especially for students who have had 
little or no previous instruj8|ion in botany, and it is 
hoped that it may also be found interesting and profit- 
able to the general reader who would learn more of the 
principles that underlie the culture of plants. 

It is expected that the instructor will amplify the 
text in proportion to the time at his command, and the 
capacity of his students. In the author's practice, the 
first three chapters have been found sufficient for a 
term of twelve weeks, and the remaining chapters, sup- 
plemented with some special work in horticulture, have 
served for a second term. 

A syllabus of laboratory work is added as an ap- 
pendix. 

It is hoped that this book may prove as useful to 
other instructors as it has proved to the author during 
its evolution. 

Madison, Wis., Feb. 15, 1897. E. S. GOFF. 



PREFACE TO THE THIRD EDITION 



Several changes have been made in the text of the 
second edition. These changes were outlined by the 
author and preserved as marginal notes in a copy used 
by him in the class-rocm. In some cases these notes 
have been inserted without change, in others where ab- 
breviated they have been amplified according to what 
is believed to be the intent of the author. This assump- 
tion is founded on intimate association with the author 
in his work in the preparation of the first edition and 
in later class work. 

In making changes an effort has been made to ap- 
proach as closely as possible to the style of the text. 

FREDERIC CRANEFIELD. 
Madison, Dec, 1905. 



ACKNOWLEDGMENTS 



The author desires to express his thanks to Prof. 
Charles R. Barnes, of the University of Chicago, Prof. 
F. W. Woll, of the Wisconsin Agricultural Experiment 
Station and Mr. F. Cranefield, the author's assistant in 
horticulture, for revision of the manuscript (of the 
first edition), and for many valuable suggestions. 

Figures 14, 15, 18, 19, 20, 21, 22, 28, 29, 30, 34, 46, 
47, 48, 49, 53, 54, 55 and 83 were copied from "Agri- 
cultural Botany," with the sanction of the author. Prof. 
M. C. Potter, of the Durham College of Science, Eng- 
land. Figures 61, 62, 63, 82, 84, 94, 98, 100, 101, 102, 
103, 113, 117, 118, 119, 120, 121, 123 and 128 are from 
''The Nursery Book," by Prof. L. H. Bailey, and are 
used by permission. Figures 31, 59, 81, 85, 99 and 130 
are from ''The Amateur Fruit Book," by Prof. S. B. 
Green, and are used by permission. Figure 32 is from 
a photograph kindly loaned by Prof. Green. Figures 
37, 39, 40, 41, 42 and 44 are copied by permission of 
the publishers from "Barry's Fruit Garden." Fig- 
ures 94 and 95 are from "How to Make the Garden 
Pay," by T. Greiner, and are used by permission. Fig- 
ures 65 and 66 were copied by permission from Bulle- 
tin No. 37, of the Rhode Island Agricultural Experi- 
ment Station. Figures 77, 78 and 79 are from cuts in 
the possession of the Wisconsin Agricultural Experi- 
ment Station. 



CONTENTS 



PAGE. 

Chapter I. — Introductory 9 — 21 

Chapter II.— The Round of Plant Life 22—118 

Section 1 — The Behavior of Seeds toward Water. 22 — 24 

2 — Germination 24 — 32 

3— The Plantlet 32— 48 

4— The Inner Structure of the Plantlet. . 48— 56 
5 — The Water of Plants and its Move- 
ments 57 — 65 

6— The Root and the Soil 65— 79 

7— The Stem 79— 82 

8— The Leaves 82— 85 

9— The Buds 86— 95 

10— The Flower 95—103 

11— The Fruit and the Seed 103—106 

12— The Gathering and Storing of Seeds.. 106—111 
13 — The Decline of Growth and the Rest 

Period 111—117 

Chapter III. — The Plants as Affected by Unfavor- 
able Environment 118 — 188 

Section 1 — The Plant as Affected by Unfavorable 

Temperature 118 — 136 

A— By Excessive Heat 118—121 

B— By Excessive Cold 121—127 

Section 2 — Methods of Averting Injury by Cold . . 127 — 136 

A — During the Dormant Period... 127 — 129 

B — During the Growing Period... 129 — 136 
Section 3 — The Plant as Affected by Unfavorable 

Water Supply 137—144 

A — By Excessive Water 137 — 141 

B — By Insufficient Water 142—144 



8 Contents. 

Chapter III. — Section 4. — The Plant as Affected by page 

Unfavorable Light 145 — 149 

A — By Excessive Light 145 — 147 

B— By Insufficient Light 147—149 

Section 5 — The Plant as Affected by Unfavorable 

Wind 150—151 

A — By Excessive Wind 150 

B — By Insufficient Wind 151 

Section 6 — The Plant as Affected by Unfavorable 

Food Supply 151—159 

A — By Excessive Food 151 — 152 

B— By Insufficient Food 152—159 

Section 7— The Plant as Affected by Parasites 159 — 186 

A — By Animal Parasites 160 — 178 

B — By Vegetable Parasites 178 — 186 

Section 8— The Plant as Affected by Weeds 186—188 

Chapter IV.— Plant Manipulation 189—270 

Section 1 — Plant Propagation 189 — 235 

A— By Seeds 190—191 

B — By Division, i. e., by parts 

other than Seeds 191—235 

Section 2— Transplanting 235 — 252 

A— Lifting the Plant 237—239 

B— Removing the Plant 239—242 

C— Replanting 242—249 

D — After Care of Transplanted 

block 250—252 

Section 3— Pruning 252—269 

A — Formative Pruning 256 — 262 

B— Stimulative Pruning 262—266 

C — Protective Pruning 266 

D—Maturative Pruning 266—267 

Chapter V.— Plant Breeding 270—280 



PRINCIPLES OF PLANT CULTURE 



CHAPTER I. 

INTRODUCTORY. 

Before taking up a systematic study of plant cul- 
ture, we may profitably consider a few principles of a 
more general nature. 

1. Close Observation offers the best means of gain- 
ing knowledge of material things. The habit of ac- 
curate discernment, and of studying the relations of 
and the reasons for things and facts as we find them, 
should be constantly cultivated. Knowledge once 
gained must be applied at the proper place, the proper 
manner and at the proper time, or the highest success 
in any calling cannot be expected. 

2. The Difference between Art and Science. Art is 
simply knowing how to do a thing without reference to 
reasons. Science considers the reasons for doing it in a 
particular manner. Art implies more or less of skill 
gained through practice. Science implies a knowledge 
of the objects to be gained by a given operation and the 
conditions affecting the process. 

An intelligent but ignorant person might be taught to 
prepare and insert a cion (386)* in the most approved 

* The numbei'S in parenthesis in the text refer to the num- 
bered paragraphs in this book, and are intended to help students 
to a better understanding of the subject. Students should be 
urged to look up these cross references. 
2 



10 Principles of Plant Culture. 

manner. This pertains to the art of grafting. The 
same person might be taught the reasons why each step 
of the process is performed in its particular manner. 
This pertains to the science of grafting. One may be- 
come a skilled grafter without learning the science of 
grafting, but he cannot graft intelligently. The arti- 
san, however skillkul, who knows only the art, cannot 
become a master w^orkman in the highest sense until he 
learns also the science that underlies his trade. 

The art of doing any kind of work is best learned by 
working under the guidance of a skilled workman. The 
science is best learned from books with the help of 
trained instructors. Science not yet wrought out, and 
hence not explained in publications, is learned by close, 
persistent and thoughtful observation and study. 

3. Environment is a term used to express all the out- 
side influences, taken as a whole, that affect a given 
object in any way. A plant or animal, for example, is 
affected by various external conditions, as heat, moist- 
ure, light, food, etc. These conditions and all others that 
influence the plant or animal make up its environment. 

4. What is Culture? The well-being of a plant or 
animal depends very much upon a favorable condition 
of environment, and with the proper knowledge, we can 
do much toward keeping the environment in a favor- 
able condition. For example, if the soil in which a 
plant is rooted lacks plant food, we can enrich it; if it 
lacks sufficient moisture, we can dampen it ; if the plant 
is shaded by weeds, we can remove them. These, and 
any other things that we can do to make the environ- 
ment more favorable, constitute culture in the broadest 



Introductory. 11 

sense of the term. A full knowledge of the culture of 
any plant implies a knowledge, not only of the plant and 
its needs, but of each separate factor in its environ- 
ment, and how to maintain this factor in the condition 
that best favors the plant's development toward some 
special end, as the production of the finest and highest 
type of fruit, flowers or seed. We should know, not 
only the soil that best suits the plant, but the amount of 
light, moisture, warmth and food in which it prospers 
best. We should know the enemies that prey upon it, 
the manner in which they work their harm, and how to 
prevent their ravages. We should know, in short, how 
to regulate every factor of environment so as to pro- 
mote the plant 's well-being to the utmost, as well as how 
to develop every desirable quality the p'ant possesses. 

5. Domestic or Domesticated Plants or Animals 
are those that are in the state of culture. In nature, 
different plants and animals struggle with one another 
for space and food. Only those best adapted to their 
environment survive, and these are often much re- 
stricted in their development. In culture, the intelli- 
gence and energy of man produce a more favorable 
environment for the species he desires to rear; hence 
domestic plants and animals attain higher development 
in certain directions than their wild parents. The cul- 
tivated potato, for example, grows larger, is more pro- 
ductive and is higher in food value than the wild po- 
tato. The finer breeds of horses and cattle are superior 
to their wild progenitors in usefulness to man. 

6. Culture Aims to Improve Nature's Methods 
rather than to imitate them. By cutting out the super- 



12 Principles of Plant Culture. 

fluous branches from a fruit tree, we enable the fruit 
on the remaining' branches to reach a higher state of de- 
velopment. By planting corn at the proper distances, 
we prevent crowding and enable each plant to attain 
its maximum growth. We should constantly study na- 
ture's methods for useful hints in culture, and the cul- 
ture of a given plant or animal should be based more or 
less upon its natural growth conditions, but the highest 
progress would be impossible if we sought only to imi- 
tate nature. 

7. Culture Deals with Life. All the products of cul- 
ture, whether obtained from the farm, garden, orchard, 
nursery or greenhouse, proceed directly or indirectly 
from plants or animals, both of which are living beings. 
A knowledge of the conditions that sustain and promote 
life, is, therefore, the foundation to a broad knowledge 
of husbandry. 

8. What is Life? We know nothing of life except as 
it is manifested through the bodies of plants and ani- 
mals. With these, we can define, within certain limits, 
the range of environment in which it can exist; we can 
hinder cr favor it; we can apparently destroy, but we 
cannot restore it. We know that it proceeds from a 
parental body similar to its own, that the body it in- 
habits undergoes a definite, progressive period of devel- 
opment, at the end of which the life disappears and the 
body loses more or less promptly its form and properties. 

9. Vigor and Feebleness are terms used to express 
the relative energy manifested by the life of different 
living beings. Certain trees in the nursery row usually 



Introductory. 13 

outstrip others in growth, i. e., are more vigorous than 
others. One pig in a litter very often grows slower 
than any of the others, i. e., is more feeble or less vigor- 
ous than any of the others. Feebleness is the opposite 
of vigor. The most vigorous plant or animal usually 
attains the largest size, and as a rule, is most satisfac- 
tory to its owner. Vigor is promoted by a favorable 
environment. It is usually greatest in rather young 
plants and animals, and declines with advancing age. 
It may be reduced by disease or improper treatment, 
and when thus reduced is often difficult to restore. Re- 
duced vigor tends to early maturity and shortened life, 
and sometimes to increased prolificacy. 

10. Hardiness and Tenderness are terms used to ex- 
press the relative power possessed by different plants or 
animals to endure extremes in their environment. The 
Oldenburgh apple endures with little harm vicissitudes 
of temperature that are fatal to many other varieties; 
in other words, it is hardier as regards temperature 
than many other varieties. The reindeer is hardier as re- 
gards cold than the horse, but tenderer as regards heat. 
The melon plant is hardier as regards heat and drought 
than the lettuce, but tenderer as regards wet or coM. 

11. Health and Disease. A plant or animal is said 
to be in health when all its organs (parts) are capable 
of performing their normal functions. An organ in- 
capable of doing this, or the being possessing such an 
organ, is said to be diseased. 

12. The Cellular Structure of Living Beings. A 
bit of vegetable or animal substance, examined under a 



14 



Principles of Plant Culture. 



microscope of moderately high power, is seen to be 




B 



made up of numerous little 
sacks or cavities, more or less 
clearly defined, called cells. 
Cells from different beings, or 
(QQ\ C from different parts of the same 
\J^=J) being, may vary much in form 

Fig. 1. Showing four indi- -, . r, 4. 4.1, ij 

viduai plants of a species and sizc, but they are seldom 

of protococcus. A shows a ^ , i -.i 

plant before commencing to large CnOUgh tO DC SCCn Wlth- 
divide into other plants. , 

B, c and D show how the out magniiymg powcr. borne 

cells divide to form other i t • 

plants. Highly magnified, of the loWCSt plants and aUl- 







Ftg. 2. Part of a filament of a species of Spirogyra, a plant 
consisting of a single row of cells united at their ends. The 
places where the cells join are indicated by the vertical lines. 
Highly magnified. 

mals consist of single 
cells (Fig. 1). Some of 
the lower plants consist 
of a single row of cells 
united at the ends (Fig. 
2) . The higher plants and 
animals are made up of 
many cells united, and j 
in these, the cells assume 
different forms and prop- 
erties in the different or- -r ■ — ■ ^^-^:=:i^=J^3^ciSQgQOo 

gans (Fig. 3). In some fig. 3. showing cells of the ap- 
ple leaf in a section from its up- 

Cases the united cells may per to its lower surface. Highly 

magnified. The spaces marked I 

be readily separated from are cavities between the cells. 

one another, which shows each cell to be more or less 




Introductory. 15 

an independent structure. As a rule, each cell is sur- 
rounded by its own closed cell-wall. 

13. Protoplasm (pro'-to-plasm). Living cells consist 
of a transparent, jelly-like substance called protoplasm, 
which manifests the various phenomena of life. Proto- 
plasm may exist either in an active or dormant state. 
In the active state it requires both nourishment and 
oxygen; in the dormant state it may exist for a consid- 
erable time with very little of either, and is far less 
susceptible to external influences than in its active state. 
The protoplasm contained in plants during their rest 
period (170), in mature air-dry* seeds, and in the 
lower animals during their torpid condition, is in the 
dormant state. 

14. Reserve Food. Active protoplasm may absorb 
nourishment in excess of immediate requirements and 
hold it as reserve food. In plants, this reserve food is 
in the form of starch, sugar or oil ; in animals it is in 
the form of fat. These substances are formed by the 
protoplasm from its crude food materials (58). The 
reserve food enables the plant or animal to live through 
limited periods of scarcity, and to meet the demands 
necessitated by reproduction (16). 

15. Growth is the normal, permanent change in the 
form of a living vegetable or animal body, and is 
usually accompanied by increase in size. It may occur 
either through expansion of cells already formed, or 
through cell multiplication. The latter may take place 
either by division of older cells into two or more smaller 
cells (Fig. 1), or by the formation of new cells within 

* Material is said to be "air-dry" when it is as dry as it will 
become by exposure to the air at ordinary temperatures. 



16 Principles of Plant Culture. 

older ones— the young cells thus formed attaining full 
size by subsequent enlargement. 

i6. Reproduction is the increase in number of li\'ing 
beings. It is one of the properties of protoplasm and 
is essentially a process of division. As living ceUs mul- 
tiply by forming new cells, so living beings, which con- 
sist of cells, multiply by the separation of a part of 
their own cells, and this separated group of cells grows 
into a complete organism like the parent. The higher 
plants multiply by seeds (155), which are separated 
from the parent plant, and each of which contains a 
young plant (53). The eggs from which young birds 
are hatched contain cells filled with living protoplasm, 
and the protoplasm of the living young of mammals is 
separated from the parent before birth. Prolificacy, 
the faculty for reproduction depends in part upon 
variety. 

i6. Reproduction is either Sexual or Non-Sexual. 
Sexual reproduction can take place, as a ru^e, only upon 
the union of cells of different sexes. It is not peculiar 
to the animal kingdom, but occurs in plants also, and 
except in rare cases, is necessary to the production of 
seeds that are capable of germination (28). It is the 
only method of reproduction in the higher animals. 
Sexual reproduction does not usually take place until 
the period of most rapid growth has passed. Non- 
sexual reproduction is independent of sex. It results 
from the direct separation of a part of the parent, 
which under favorable conditions develops into a com- 
plete individual. It occurs when plants multiply by 



Introductory. 17 

means other than by seeds, as by non-sexual spores (52), 
bulbs (352), stolons (348), cuttings (358), etc., and it 
is a common method of reproduction in certain of the 
]ower animals, as plant lice (aphidae). 

i8. Heredity and Variation. The offspring of a 
plant or animal tends to be like the parent or parents. 
But no t^A'o beings can be begotten and developed in 
exactly the same environment, and since environment 
always affects the individual more or less, it follows 
that no two individuals can be precisely alike. Yaria- 
ticn in the offspring may take place in any direction, 
as in the size or color of the flower, the sweetness or 
juiciness of the fruit, the prolificacy, the vigor (9), or 
the hardiness (10), etc. It follows that in culture cer- 
tain individual plants or animals are more desirable to 
the cultivator than others, because the individuals pos- 
sess different qualities. 

19. The Principle of Selection. Since the offspring 
tends to resemble the parent or parents, we may gradu- 
ally improve plants or animals in the direction of 
greater usefulness by selecting the most desirable indi- 
viduals for reproduction. For example, by saving and 
planting seeds from the plants that produce the finest 
petunia or pansy blossoms, we secure finer flowers than 
if we gather plants without regard to parentage. 

20. Breeding in plants and animals is reproduction, 
watched over and directed by man, with reference to 
securing special qualities in the offspring. It is based 
on the principle that the peculiarities of the parent or 
parents tend to be reproduced, and may be intensified, 
in the descendants. But before we are prepared for 



18 Principles of Plant Culture. 

the study of breeding, we need to know something of 
the principles of classification. 

21. Classification is the arrangement of the different 
kinds of plants and animals into groups and families 
based on individual resemblances. If we examine plants 
as they are growing in nature, we may observe (a) that 
there are many plants of the same kind, and {h) that 
there are many kinds of plants. The different plants 
or animals of the same kind are called individuals, and, 
in general, we may say that the different kinds of 
plants or animals are called species (spe'-cies). But 
these simple distinctions are not sufficient to satisfy the 
needs of natural history. We might say, for example, 
that the violet is one kind of plant and the oak is an- 
other, which is true ; but there are also different kinds 
of violets and different kinds of oaks. We might say 
that the apple is one kind of plant and the pear is an- 
other, but there are different kinds of apples, as the 
crab apple and the common apple, and there are differ- 
ent kinds of crab apples, and of common apples. We 
must not only arrange the kinds of plants into groups, 
but we must have groups of different grades. For ex- 
ample, botanists call each distinct kind of plant, as 
the sugar maple, the white oak and the dandelion, a 
species. Then the species that rather closely resemble 
each other are formed into groups, each of which is 
called a genus (ge'-nus), plural, genera (gen'-e-ra) as 
the sugar maple and the soft maple ; the white oak, the 
red oak and the bur oak; the raspberry and the black- 
berry; and the apple, pear and quince. Then the gen- 
era that resemble each other, as the one containing the 



Introductory. 19 

apple, pear and quince, and the one containing the 
plum, cherry and peach, are formed into other groups 
called families.* Thus families are made up of genera, 
and genera are made up of species. There may be, also, 
different varieties in the same species, as the different 
varieties of apple, pea, or strawberry. 

An extensive retail bookstore furnishes an object les- 
son in classification, though we must remember that in 
natural history it is usually the names and descriptions 
of plants and animals that are classified, and not the 
plants and animals themselves. In the bookstore, we 
will observe that the books are not placed upon the 
shelves without order, but that they are arranged in 
groups. Different copies of the same work are placed 
together. Different works on the same subject, as 
Gray's botany. Wood's botany, Bessey's botany are also 
placed in a larger group. Then all the scientific books 
are formed into a still larger group, as are the books of 
fiction, the books of poetry, the music books, etc. Com- 
paring this arrangement with that employed in natural 
history, each separate work, as Gray's Manual of Bot- 
any, Thomas' Fruit Culturist, Bunyan's Pilgrim's 
Progress, etc., would correspond to a species,! and the 
different copies of the same work would correspond to 
individuals. The books treating of the same general 
subject, as the different works on geology, botany or 
arithmetic would correspond to genera, and the differ- 
ent classes of books, as scientific books, books of fiction. 



* Related families are often further united into orders. 

t It should not. however, be understood that the different spe- 
cies of plants and animals are always as readily distinguished as 
are the different works in a bookstore. 



20 Principles of Plant Culture. 

etc., would correspond to families. There would also 
be copies of the same work in different buildings which 
would correspond to varieties. 

22. Scientific Names are given to plants and ani- 
mals because the common names by which they are 
known are so often local. For example, quack grass, 
one of our common troublesome weeds, is known by at 
least seven different common names in this country 
alone, and yet, in a given locality it is often known by 
only one name. Its scientific name, however, Agropy- 
rum repens (a-gro-py'-rum re'-pens), is the same in all 
languages and countries. Scientific names are usually 
Latin and consist of two words. The first word is the 
name of the genus to which the plant or animal be- 
longs, and is called the generic (ge-ner'-ic) name; the 
second word designates the species, and is called the 
specific (spe-cif'-ic) name. For example, Pyrus mains 
(py'-rus ma'-lus) is the scientific name of common ap- 
ple, Pyrus being the genus to which the apple belongs, 
and mains designating which species of the genus is 
meant. 

23. Crosses and Hybrids (hy'-brids). We have seen 
that in sexual reproduction, a union of male and female 
cells is almost always essential (17). When these cells 
proceed from two individuals of different varieties (21, 
436), the offspring is called a cross; when they proceed 
from individuals of different species, it is called a hy- 
hrid. Hybrids are possible only between closely- allied 
species and are often incapable of reproduction, in 
which case they are said to be sterile. The mule, which 
is a hybrid between the horse and the ass, is a familiar 



Introductory. 21 

example of a sterile hybrid. Sterile hybrids are not 
uncommon in plants. A hybrid that is capable of re- 
production is called a fertile hybrid. 

Hybrids and crosses may resemble both parents about 
equally or they may resemble one parent more than the 
other. They sometimes differ materially from either 
parent. The offspring of crosses and fertile hybrids is 
generally variable in proportion as their parents were 
different from each other, and this variability may con- 
tinue through several generations. 

24. The Theory of Evolution, now generally ac- 
cepted by naturalists, assumes that the higher plants 
and animals have been gradually evolved from lower 
forms, through the principle that those individuals pos- 
sessing peculiarities best fitting them to endure the ad- 
verse conditions of environment have survived and per- 
petuated their kind, while others have perished. 

25. Parasites. Both plants and animals are subject 
to being preyed upon by other, usually smaller, plants 
and animals, that live upon or within their bodies, con- 
suming the tissues of their bodies or their reserve food. 
Plants or animals that derive their nourishment from 
other plants or animals are called parasites (par'-a- 
ites) or parasitic. The plant or animal from which a 
parasite derives its nourishment is called a host. Para- 
sites are often microscopic in size. They are generally 
more or less injurious to their host, and form one of 
the most fruitful sources of disease (270). Some, how- 
ever, as the micro-organisms of the roots of clover and 
other leguminous plants, are beneficial (112). 



CHAPTER II. 

THE ROUND OF PLANT LIFE. 

The earlest stages of plant growth occur in the seed, 
hence this is an appropriate place to commence our 
study. We will first consider 

Section 1. The Behavior of Seeds Toward Water. 

26. Seeds Absorb Water when placed in contact with 
it. If we fill a bottle with air-dry beans, then pour in 
all the tepid water the bottle will contain, taking care 
to shake out the air bubbles, and place the bottle in a 
warm room, the beans will soon swell until they have 
pressed each other quite out of shape, and no water 
will be forced out of the bottle. This shows that the 
beans have absorbed the water and have swollen in con- 
sequence. This quality of absorbing water by contact, 
at ordinary temperatures, is possessed to a greater or 
less extent by most seeds, and indeed by nearly all air- 
dry vegetable material. It is unnecessary that the seeds 
be covered with water to enable them to absorb it. If 
in contact with any moist medium, as a damp cloth or 
damp earth, they will absorb moisture and swell. 

27. The Rate at which Seeds Absorb Water de- 
pends upon several conditions, as 

a — The water content of the medium with which they 
are in contact. If we place one lot of beans in water, a 
second in wet earth and a third in slightly damp earth. 



The Behavior of Seeds Toward Water. 23 

we shall find that the first lot will swell the fastest, the. 
second next and the third slowest. Few seeds will ab- 
sorb enough water from damp air at ordinary tempera- 
tures to swell much. 

b—The points of contact. If we weigh, two lots of 
100 beans each, on a delicate balance, and mix each lot 
with well-crumbled, moist loam in a fruit- jar, packing 
the loam tightly in one of the jars, and leaving it as 
loose as possible in the other, close both jars to prevent 
evaporation, and after twenty-four hours sift the beans 
out of the loam and weigh the two lots again— we shall 
find that the beans in the jar containing the compacted 
loam have increased more in weight than the others. 
This indicates that the feeans in this jar have absorbed 
water faster than those in the other, because they were 
in contact with the moist loam at more points. 

G— Temperature. If we fill two bottles with beans, 
adding ice water to one, placing it in a refrigerator, and 
lukewarm water to the other, setting it in a warm room, 
we shall find that the beans in the latter bottle will swell 
more rapidly than those in the former. This shows that 
a warm temperature favors the absorption of water — a 
fact that is true of all seeds. The same would have 
been true had we planted the beans in two samples of 
moist earth, placing these in different temperatures. 

d—The nature of the seed-case.* In the bean, Indian 



* The term seed-case is here used to designate the outer cov- 
ering of the seed as the word seed is understood by the seedsman 
or planter. Every seed, as we buy it in the market, or when 
ready for planting, has one or more covering layers. In the pea- 
nut, for example, what we here call the seed-case is commonly 
called the shuck; in the cocoanut it is called the shell; in the 
bean and Indian corn it is more often called the skin. In botany, 
the outer coverings of seeds are given different names, as peri- 
carp, testa, etc., according to their exact office in the make-up of 



24 Principles of Plant Culture. 

corn, wheat and many other seeds, the seed-case is of 
such a nature that it absorbs and transmits water read- 
ily. In certain seeds, however, as of the honey locust, 
canna, thorn apple, etc., especially if the}^ have been 
allow^ed to become dry, the seed-case does not readily 
transmit water at growing temperatures. Such seeds 
may lie for weeks, and even months, in tepid water 
without swelling, but when the water is heated to a 
certain degree, they swell promptly, a fact often turned 
to account by nurserymen (36). AA^e cannot always 
judge by the appearance of a seed-case whether it will 
transmit water readily or not. 

Section II. Germination. 

28. AVhat is Germination ? If we place a few viable* 
grains of Indian corn between the moist cloths of a 
seed-tester (Fig. 6), cover with the glass and place in a 
warm room, we shall observe if we examine the corn 
frequently, that a change, aside from the swelling, will 
soon take place in at least a part of the grains. The 
seed-case will be burst by the pressure of a tiny white 
shoot from beneath. AVe say that such grains have 
sprouted or have commmenced to germinate (ger'-mi- 
nate), i. e., have taken the first visible step toward de- 
veloping into a plant. 

AVe have seen that the mature seed contains proto- 
plasm in its dormant condition (13). At a suitable 
temperature, the protoplasm, on the absorption of 

the plant. To avoid explaining the technicalities of a complex 
subject, it seems preferable to adopt a term that will include the 
various words used in botany to designate the outer coverings 
of seeds. 

* A viable (vi'-a-ble) seed is one that is capable of germina- 
tion. Not all seeds are viable (164). 



Germination. 25 

water, resumes its active state, and the cells of a certain 
part of the seeds begin to increase in size and to divide 
(15), causing the tiny shoot to burst through the seed- 
case. Germination is completed when the young plant 
(plantlet) is sufficiently developed to live without fur- 
ther aid from the seed. 

29. Moisture is Essential to Germination. Air-dry 
corn or other seeds will not germinate if kept however 
long in a warm room, whereas viable seeds, that have 
absorbed water until fully swollen, will usually germi- 
nate if exposed to air of a suitable temperature, under 
conditions that prevent their loss of moisture. This 
shows that a certain amount of moisture must be ab- 
sorbed by the seed before germination can take place. 
Seeds must be nearly or quite saturated with water be- 
fore they will germinate. 

In culture we plant seeds in some moist medium; 
usually the soil, in order that they may absorb moisture 
and germinate, and thus develop into new plants. 

30. Warmth is Essential to Germination. Had we 
placed the seed-tester mentioned in paragraph 28 in a 
refrigerator in which the temperature never rises above 
41° F., instead of in a warm room, the corn grains 
would not have germinated however long they remained 
there. This shows that a certain degree of warmth is 
also necessary to germination. Without this, the pro- 
toplasm of the seed cannot assume its active state (13). 
The lowest (minimum) temperature at which seeds can 
germinate varies considerably with different species, 
and so does the temperature at which they germinate 

soonest (optimum) as also the highest (maximum) tem- 
3 



26 Principles of Plant Culture. 

perature at which they can germinate. The following 
table* shows approximately the minimum, optimum and 
maximum temperatures at which seeds of the species 
named germinate. 

MINIMUM. OPTIMUM. MAXIMUM. 

Barley 41° F 77°-88°F 99°-lll°F. 

Bean (Scarlet runner) 41 77-88 88-99 

Buckwheat 41 :93 115 

Clover (red) 88-99 99 -111 Ill -122 

Cucumber 60-65 88 -99 Ill -122 

Flax 41 77-88 88-99 

Hemp 32-41 99-111 Ill -122 

Indian Corn 41-51 99 -111 Ill -122 

Lucern (Alfalfa) 88-99 99 -111 Ill -122 

Melon 60-65 88 -99 Ill -122 

Oat 32-41 77 -88 88 -99 

Pea 32-41 77 -88 88 -99 

Pumpkin 51-60 93 -111 Ill -122 

Rye 32-41 77 -88 88 -99 

Sunflower 41-51 88 -99 99 -111 

Wheat 32-41 77 -88 88 -108 

These temperatures refer to the soil or other medium 
with which the seeds are in contact, and not to the 
atmosphere. 

When moisture is sufficient, the time from planting to 
sprouting decreases rapidly as we approach the opti- 
mum temperature. In an experiment, Indian corn 
sprouted in one-third of the time at 88° F. that it re- 
quired to sprout at 61°. 

Seeds of tropical plants usually require higher tem- 
peratures for germination than those of temperate 
plants. 

31. Free Oxygen is Essential to Germination, If 
we place in the bottom of each of two saucersf a layer 

* Compiled from Haberlandt and Sachs. 

t If flower-pot saucers are used they should first be well soaked 
in water, so that they will not extract water from the soil. 



Germination. 27 

of puddled* clay or loam, put 25 viable beans on the 
soil in each saucer, then fill one saucer with moist sand 
and the other with puddled clay or loam, pressing the 
latter down very closely around the beans, cover both 
saucers with a bell-jar, and place in a warm room for 
two or three days, we shall find that the beans covered 
with the sand will sprout promptly, while those covered 
with the puddled soil will not (Fig. 4). In the sand- 




FiG. 4. In the left hand saucer beans were planted in puddled 
soil. In the other, they were covered with sand. They failed to 
germinate in the puddled soil, because their contact with oxygen 
was cut off. (From nature.) 

covered saucer the air between the grains of sand has 
had access to the beans, while in the other air has been 
shut out, which explains the sprouting of one lot of 
seeds and the failure of the other. About one fifth of 
the atmosphere is free oxygen, i. e., oxygen that is not 
chemically combined with any other substance. 

We have seen that protoplasm in its active state re- 
quires oxygen (13). Unless seeds are so planted that 
a certain amount of this free oxygen can reach them 
they cannot germinate. f Ordinary water contains a 
little free oxygen, but not enough to enable many kinds 
of seeds to germinate in it, though the seeds of some 
water plants, as the water lily and rice, will germinate 

* Soil is said to be puddled when wet and packed until it is 
in the consistency of putty. 

t This probably explains why very deeply-planted seeds rarely 
germinate. 



28 



Principles of Plant Culture. 



in water. But even these will not germinate in water 
that has been boiled long enough to expel the o:5^gen, 
and is placed under conditions that prevent its ab- 
sorption again (Fig. 5). 

We thus see that seeds require three conditions be- 
fore they can germinate, viz., a certain amount of 
moisture, of warmth and of oxygen. In planting seeds, 
we should consider all these requirements. 

32. Prompt Germination is Important. As a rule, 
the sooner a seed germinates after it is planted, the 
better, for it is generally in danger of being destroyed 
by animals or fungi, and the plantlet probably loses 

vigor by too slow 
development. 
Weeds may also be 
gaining a start if 
germination is de- 
layed. We should, 
therefore, treat 
both the seed and 
the soil in the way 
that favors prompt 



germination. 

Fig. 5. In the left bottle, the water, which had been boiled to 
expel the oxygen, was covered with oil to prevent it from absorb- 
ing oxygen again, hence the rice seeds in it could not germinate. 
In the right bottle the water was not covered, and so could ab- 
sorb oxygen, permitting the seeds to germinate. (From nature.) 

33' Compacting the Soil about planted seeds 
Hastens Germination by multiplying their points of 
contact with the moist earth (276). When the soil is 
becoming drier day by day, as it often is in spring, 
compacting the soil about planted seeds materially 




Germination. 29 

hastens their germination and often secures germina- 
tion that without the compacting might be indefinitely 
postponed. The hoe, the feet, a board or the hand- or 
horse roller may be used to compact soil over planted 
seeds. Seeds planted in flower pots or in boxes or 
beds in the greenhouse or hot-bed, however, should not 
have the soil unduly packed. 

34. Planting should be Deferred until the Soil be- 
comes Warm. Seeds cannot germinate promptly until 
the temperature of the soil in which they are planted 
approaches the optimum for their germination (30) 
during the warmer part of the day, and germination is 
promoted little, if at all, by planting before this time. 

35. Germination may be Hastened by Soaking 
seeds before planting. Since seeds cannot germinate 
until nearly or quite saturated with water (29), and 
since they absorb water faster from a very wet than 
from a damp medium {21a), and in a warm than in a 
cool temperature (27c), we may hasten germination a 
little if the soil to receive the seeds is only slight^, y 
moist, by soaking the seeds before planting in warm or 
slightly hot water until they have swollen. This method 
is sometimes practiced by gardeners with sweet corn 
and certain other seeds, and its use might possibly be 
extended with profit. The water should be heated only 
to 110° or 120° F. and the soaking may be continued 
until the seeds have fully swollen. 

Soaking is most important with seeds having seed- 
cases that do not readily transmit water at growing tem- 
peratures, as in the honey locust, canna, thorn apple, 
hawthorn, holly, peony, etc. (27cZ). Such seeds, par- 



30 Principles of Plant Culture. 

ticularly if they have been allowed to become dry, are 
generally soaked in hot water until swollen, before 
planting, otherwise they might lie in the ground for 
months and even years before germinating. In treat- 
ing such seeds with hot water, unless the temperature 
at which they swell is known, the water should be 
heated very gradually until the seeds begin to swell, 
when it should be maintained at that temperature until 
they are fully swollen. It is said that seeds of the honey 
locust may be immersed for a time in boiling water with- 
out destroying their vitality, but such treatment is not 
to be recommended for any seeds. In seeds of this class, 

36. Germination is sometimes Hastened by Cracking 
or Cutting Away part of the Seed-Case. To favor 
the absorption of water, nurserymen often drill or file 
a hole through the bony seed-cases of nelumbium seeds, 
or crack dry peach and plum pits in a vise or with an 
implement resembling a nutcracker {27 d). 

37. Seeds may Fail to Germinate from a variety of 
causes, even when exposed to the proper degree of 
warmth, moisture and oxygen. They may be too old 
(164), they may not have been sufficiently mature when 
gathered (162), they may have become too dry (168), 
they may have been subjected to freezing before suffi- 
ciently dry (166), they may have been stored while 
damp and thus subjected to undue heating, or they 
may have been damaged by insects or fungi (321) 
either before or after maturity. Defects of these kinds 
are not always visible, hence 

38. Seeds should be Tested before Planting to learn 
if they will germinate. It is unnecessary to plant 



Germination. 



31 



seeds in soil to test them, since the seed-tester shown in 
Fig. 6 is much more convenient. This useful device con- 
sists of two circular pieces of clean, moderately thick 
cloth of rather loose texture, a table plate that is not 
warped, and a pane of glass large enough to cover the 
plate. The cloths are dipped in water, and squeezed a 
few times while under the water to press out the air. 




Fig. 6. Showing a simple seed-tester, adapted to farmers' and 
gardeners' use. 

They are then wrung out until moderately wet, and 
spread over the bottom of the plate as shown, and the 
seeds to be tested are placed between them. It is well 
to use a hundred or more seeds of each sample, as a 
larger number will show the per cent of vitality more 
accurately than a smaller one, and the lot should al- 
ways be well mixed before taking the sample. The 
plate should be kept covered with the glass to prevent 
evaporation from the cloths, and it may be placed in 
any room of comfortable living temperature. The seeds 
should be frequently examined, and may be removed as 
they sprout, when by subtracting the number that fail 
to sprout from the number put in, the per cent of vi- 
tality may be readily computed. The cloths should be 



32 Principles of Plant Culture. 

placed in boiling water a few minutes before using them 
for a second test, to destroy any spores or mycelia of 
mold with which they may have become infected. 

39. The Time Required for Germination varies 
greatly in different kinds of seeds. In lettuce seed, the 
tiny white shoot often breaks through the seed-case 
within twenty-four hours from planting, while celery 
seed requires several days to germinate to this extent. 
The seeds of many plants will not germinate the same 
season they are formed, even if planted under the most 
favorable conditions (162). 

Individual seeds of the same kind and of the same 
sample often vary greatly in the time required for ger- 
mination. Even in seeds that germinate soonest, as 
lettuce and radish, some individuals will not germinate 
until several days after the majority have germinated. 
Seeds of tobacco and purslane* sometimes continue to 
germinate through several successive seasons. The rea- 
sons for these variations are not known. 

Section III. The Plantlet. 

By watching the germination of seeds, we may learn 
some interesting facts. Viable seeds will usually germi- 
nate freely on the surface of well-moistened soil or sand, 
if we provide a damp atmosphere above them by cover- 
ing with a bell- jar or otherwise, for light does not hin- 
der germination. One of the interesting facts connected 
with germination is, that the first shoot, called 

40. The Hypocotyl* (hy'-po-co'-tyl) Grows Down- 
ward, on emerging from the seed-case (27t^), no matter 

*Portulaca oleracea. 



Tlie Plantlet. 33 

in what position the seed is placed. It will curve in a 
semi-circle if necessary, to bring its rounded point in 
contact with the soil. But the hypocotyl is not always 
able to enter the soil, unless the seed is covered more 
or less, because the resistance offered by the soil is often 
greater than the weight of the seed. On this account, 
as well as to insure a supply of moisture, it is best to 
cover most seeds at planting, or at least to press them 
well into the soil (51). In nature, seeds usually be- 
come more or less covered, and these not covered gen- 
erally fail to germinate. 

41. The Seed-Case in Germination. After germina- 
tion commences, the seed-case is of no further use. It 
has fulfilled its purpose, which is to protect the seed 
from the time of its maturity until the conditions ar- 
rive for germination, and is henceforth a hindrance to 
germination in many plants, as it must be torn asunder 
by the expanding plantlet. If we watch the germina- 
tion of squash or pumpkin seeds through the different 
stages, we may discover that nature has made a special 
provision to help the plantlet in escaping from the seed- 
case in these plants. As the hypocotyl curves down- 
ward, a projection or hook is formed on the side toward 
the seed, which holds the seed-case down while the seed- 
leaves are pulled out from it. The action of this hook 
is shown in the accompanying figures. Sometimes, as 
shown in C, the point of the seed-case breaks, permit- 
ting the hook to slip off, and if the seed happens to be 
planted edgewise or 'v\dth the point downward, the hook 
often fails to catch the seed-case, as in D, and so the 

* Often called radicle and caulicle. 



34 



Principles of Plant Culture. 



plantlet emerges from the soil without freeing itself 
from the seed-case and is hampered for a time. This 
provision is peculiar to the pumpkin family,* to which 
the pumpkin, squash, cucumber and melon belong, 
though other provisions which accomplish the same end 






Fig. 7. Showing nature's provision to enable the pumpkin 
plantlet to escape from the seed-case. In A, the hook on the 
hypocotyl is attached to the lower half of the seed-case. B shows 
the same after germination is farther advanced. A fully-germi- 
nated pumpkin plantlet is shown at Fig. 8. 

are found in a few other families, but many plants are 
considerably held back by the seed-case during ger- 
mination. 

42. Seeds of the Pumpkin Family should be Planted 
Flatwise, rather than edgewise or endwise, since in this 
position they most readily free themselves from the 
seed-case. 

43. Some Plantlets Need Help to Burst the Seed- 
Case. In many seeds having hard and strong seed- 
cases, as the walnut, butternut and hickory nut and the 



* Natural order Cucurbitaceae. 



The Plantlet. 



35 



pits of the plum, peach and cherry, the enlarging plant- 
let is often unable to burst the seed-case, hence germi- 
nation cannot take place unless assisted by the expand- 
ing power of frost, or long exposure to moisture which 
softens the seed-case, or unless the seed-case is cracked 
before the seeds are planted (36). 

44. The Roots promptly start, as the hypocotyl 
emerges from the seed-case — the main {primary) root 
from its point, and the branch {lateral) roots from its 




Fig. 8. Plantlet Fig. 9. Plantlet Fig. 10. Plantlet Fig. 11. Plantlet 
of pumpkin. of bean. of Indian corn. of pea. 

In the pumpkin and bean, the seed-leaves (cotyledons) are 

lifted above the surface of the soil in germination. 

In the pea, the cotyledons are not lifted above the surface of 

the soil in germination. 

side. Sometimes root-hairs (100) may be distinctly 
seen, especially when seeds germinate in the seed-tester 
(38). 

By studying Figs. 8 to 11, we may learn more of the 
germinating process. 

45. The Cotyledons (co-ty-le'-dons). In the bean 
and pumpkin, the seed, or what remains of it, seems to 



36 Principles of Plant Culture. 

have separated into two parts that are united at one 
end— the cotyledons or seed-leaves. In the bean and 
pumpkin, the cotyledons form a pair of clumsy leaves, 
which in the bean point downward at first, but after- 
wards become upright, by the straightening of hypo- 
cotyl beneath them. We observe that the pea has also 
a pair of cotyledons (c), which have not separated to 
the same extent as those of the bean and pumpkin and 
are still beneath the soil. The corn, in common with 
other plants of its class, as sorghum, sugar cane, the 
reeds, grasses, etc., has but one cotyledon, and that is 
not easily seen without dissecting the seed. In Fig. 14, 
which shows a cross-section of the germinating corn 
grain, the cotyledon appears at cot. 

The plants having two cotyledons form a very im- 
portant class in botany, known as Dicotyledones (di-co- 
tyl-e'-dones) ; those having but one cotyledon form a 
class known as Monocotyledones (mo'-no-co-tyl-e'- 
dones). There is also a class, including the pine, fir 
and other conifers, that have several cotyledons. 

46. The Hypocotyl Develops Differently in Differ- 
ent Species. In the pea (Pig. 11) and some other 
plants, the cotyledons remain in the soil, while in the 
bean and pumpkin, they have been lifted bodily into 
the air. This striking difference is due to the fact that 
in the pea, the hypocotyl lengthens very little in ger- 
mination, while in the bean and pumpkin, it lengthens 
comparatively very much. 

47. Seeds in which the Hypocotyl Lengthens in 
germination Must Not be DeepEy Planted. When 
seeds of this class, which includes many plants beside 



The Plantlet. 



37 




the bean and pnmpkin, are planted in soil, the cotyle- 
dons must be forced through the soil above them, an 

act requiring considerable en- 
ergy. If such seeds are covered 
with much soil, the plantlet is 
often unable to lift its cotyle- 
dons to the surface, and hence 
must perish. Fig. 12 shows two 
bean plantlets that tore off their 
cotyledons in the vain attempt 
to lift them through five inches 
of soil. The plantlet of wheat, 
barley and oats, though much 
smaller and weaker than that of 
the bean, readily grows through 
this depth of soil, because the 

cotyledons from being too ^W poiutcd shoot (plumulc 

deeply planted. (55) ) ^f ^^^^^ ^i^^^^ readily in- 

sinuates itself between the soil particles and comes to 
the surface with little expenditure of energy, even when 
deeply planted. Plantlets of the larger beans usually 
fail if the seeds are planted three inches deep in a 
clay soil that bakes above them. Those of the castor 
bean,* though very robust, can hard]y lift their cotyle- 
dons through one inch of soil, while those of the pea, 
though much more slender, readily grow through four 
to six inches. Apple seeds planted in autumn on clay 
soil, usually fail to germinate the following spring 
unless covered with sand or humus, or carefully 
mulched, because the plantlets are unable to lift their 
cotyledons through a baked surface soil. 

* Rlcinus. 



Fig. 12. Showing two bean 
plantlets that tore off their j-i-pTT- 



38 



Principles of Plant Culture. 




48. The Vigor of the Plantlet is generally in Pro- 
portion to the Size of the Seed. This is true not only 
between different kinds of seeds, but between different 

seeds of the 
same kind. The 
larger beans, 
the horse chest- 
nut and the 
walnut form 
much stronger 
plantlets than 
clover, timothy 
and tobacco, 

Fig. 13. Showing navy bean plants grown from and the largest 
large seeds (left) and from small seeds (right). 

and plumpest 
specimens of any sample of seed usually form stronger 
plantlets than the smaller and more shrunken specimens. 
Growers of lettuce under glass are sometimes able to 
raise one more crop during the winter by sowing 
only the largest seeds than when the seed is sown with- 
out sifting. The practice of sifting seeds before plant- 
ing, and rejecting the smaller ones, should be more 
generally followed (Pig. 13). 

49. The Earlier Germinations from a sample of seed 
often Form More Vigorous Seedlings than the Later 
Ones. This is one of nature's method for preserving 
the vigor of plants. The stronger seedlings overtop the 
later and feebler ones and crowd them out of exist- 
ence. We should profit by this hint and reject the later 
plants in the seed-bed. ' 

50. How Deep should Seeds be Planted? We have 
seen that one object of planting seeds in the soil is to 



The Planilet. 39 

place them in contact with moisture (29). Since the 
plantlet must force its way through the soil that covers 
the seed, the less the depth of this soil, other things 
equal, the less energy and the shorter time are required 
for the plantlet to reach the surface. Therefore, seeds 
should not he planted deeper than is necessary to irvsure 
the proper supply of moisture. 

Small seeds, as of lettuce, celery and carrot, produce 
such weak plantlets that it is unsafe to cover them suf- 
ficiently to insure the proper moisture supply in dry 
weather. We must, therefore, plant such seeds so 
early in spring that the soil has not had time to become 
dry, or if necessarily planted later, we must depend 
largely upon artificial watering. 

51. Very Small Seeds, as of petunia and tobacco, 
Should Not Be Covered with soil at all, but may be 
pressed down into fine loam with a board or otherwise, 
and must be watered often with a fine-rose watering-pot. 
When small seeds are sown in full exposure to sunlight, 
it is well to shade the surface with paper or a muslin- 
covered frame, to check evaporation until the plantlets 
appear. Small seeds are sometimes covered with a thin 
layer of spagnum moss that has been rubbed through a 
sieve. This helps to retain moisture in the surface soil. 

52. Ferns are Grown from Spores* sown on the sur- 
face of fine soil in a propagating frame (369), in which 



* Spores are the chief reproductive bodies in plants that pro- 
duce no seeds, as ferns, mushrooms, mosses, etc. They are usually 
so small as to be barely visible to the unaided eye. The dust 
that escapes from a puff ball when it is squeezed or from a 
bunch of corn smut is formed of the spores of these plants. 
Spores usually consist of a single cell, in which respect they 
differ materially from seeds, which contain a more or less devel- 
oped plantlet (53). 



40 Principles of Plant Culture. 

the air is kept very moist and the surface of the soil 
never becomes dry. 

53. The Plantlet is Visible in the Seed. If we boil 
seeds of the four kinds shown in Figs. 8 to 11, or of 
other kinds, in water until they are fully swollen, and 
then carefully dissect them, using a magnifying glass 
when necessary, we may observe that the plantlet is 
present compactly folded up in the seed. Germination 
(28) is really little more than the unfolding and ex- 
pansion of this plantlet. The plantlet as it exists in 
the seed is called the embryo (em'-bry-o). 

54. The Endosperm* (en'-do-sperm). From the sec- 
tion of the corn grain shown in Fig. 14, it appears that 




Fig. 14. Cross-section of germinating Indian corn grain. A 
endosperm; Cot cotyledon; Cau hypocotyl; PI plumule. Slightly 
magnified. (After Frank). 

in this seed, unlike the pea, bean and pumpkin, the 
plantlet and seed-case do not make up the whole bulk of 
the seed. The remaining part shown at A, consists 

* Called also albumen. 



The Plantlet. 41 

mainly of cells containing starch grains and oil drops, 
which serve as food for the plantlet during germina- 
tion, since active protoplasm cannot exist without nour- 
ishment (13). In the pea, bean, pumpkin and other 
seeds of this class, the food supply, instead of being 
stored by itself, as in the corn-grain, is contained 
within the plantlet or embryo— mainly in the fleshy 
cotyledons. When the food supply of the seed is sep- 
arate from the embryo, as in corn and many other seeds, 
it is called the endosperm. 

It is the food supply of seeds that makes them so 
valuable as food for animals. 

55. The Plumule (plu'-mule). If we look between 
the cotyledons of the bean plantlet (Fig. 9), at the point 
of their union with the hypocotyl, we may see a pair 
of tiny leaves, and by carefully separating these if need 
be, with the point of a pin, we may discover a minute 
projection — the growing point (66) of the stem between 
them. These leaves, with the growing point, form the 
plumule— the terminal bud of the plantlet. These tiny 
leaves become the first true leaves, and the growing 
point between them develops into the stem and later 
leaves. By close examination we ' may make out the 
plumule in Figs. 8, 10 and 11. In the pea and corn, 
it has already made considerable growth. ; 

56. Thus we see that the plantlet or seedling con- 
sists of three parts, viz., the hypocotyl, the cotyledons 
(in some plants cotyledon) or seed-leaves, and the plu- 
mule or terminal bud. 

57. Chlorophyll (chlo'-ro-phyll). Soon after the 

plantlet emerges from the seed-case, a green color ap- 
4 



42 



Principles of Plant Culture. 



pears in the parts most exposed to light. This is due 
to the formation within the cells of chlorophyll— the 
green coloring matter of plants. Chlorophyll forms 
only in light, and when a plant containing green leaves 
is kept for a time in the dark, as when celery is banked 
up with earth, the chlorophyll disappears and the green 
parts become white. The chlorophyll saturates definite 
particles of protoplasm, called chlorophyll bodies, and 
since the cell-walls and protoplasm are transparent in 
the younger cells, the chlorophyll bodies give the parts 




Fig. 15. Showing cross-section through leaf of Fagus sylvatica. 
C chlorophyll bodies; Ep epidermis of upper surface of leaf; Ep- 
epidermis of lower surface; K cells containing crystals; PI palis- 
ade layer; F vascular bundle; St stoma; I spaces between the 
cells (intercellular spaces). Highly magnified. (After Strasburger.) 

containing them a green color. Fig. 15 shows the dis- 
tribution of the chlorophyll bodies in the cells of a por- 
tion of a leaf of the beech. They appear as minute 
globules, w^hich in this case are mostly located near the 
cell-walls. They are most numerous near the upper 
surface of the leaf — the part most exposed to the sun's 
rays. 

58. No Food can be formed Without Chlorophyll. 
By the agency of chlorophyll, the chlorophyll bodies ab- 



The Plantlet. 43 

sorb energy in the form of light. This energy the 
chlorophyll body uses to take to pieces the carbonic 
acid, mineral salts and water absorbed from the air and 
the soil, and to recombine them into foods of various 
kinds which can be used by the protoplasm in making 
new^ parts and repairing waste {Assimilation (as-sim'- 
i-la-tion)). Until this food preparation commences, no 
new plant substance has been formed. It is true that 
new cell-walls and new protoplasm may be formed from 
the food supply of the seed before chlorophyll appears, 
but until chlorophyll is formed, and food preparation 
begins, the whole plantlet with what- 
ever remains of the seed, when dried, 
weighs no more than the seed 
weighed at the beginning. The ma- 
terial formed for food is starch, or 
some substance of similar composi- 
tion (sugar or oil), which, after un- 
FiG 16. Showing- dcrgoing chemical changes if need 
i?'re^ser^T?ood'Tn^a be, to render it soluble, is distrib- 
iy^^mag£fi?d.°' ^^ ' tributcd throughout the plant to be 
built up into cell-walls and protoplasm, or to be held 
as reserve food (14). 

Food preparation and assimilation are not necessarily 
simultaneous, but either may proceed without the other. 
Only plants can prepare food from mineral sub- 
stances. The food of animals must all have been first 
formed by plants. 

59. The Sources of Plant Food. By observing plant- 
lets of the bean or pumpkin a few days after germina- 
tion, we may discover that the cotyledons, which were 




44 Principles of Plant Culture. 

at first so plump, have shriveled to a mere fraction of 
their former size. They have shriveled because the 
food contained by these parts has been absorbed by the 
developing plantlet. The patrimony furnished by the 
seed is quickly exhausted. Whence then comes the 
food that is to complete the development of the plant? 
Aside from the carbonic acid already mentioned (58), 
several other substances are required to build up the 
plant structure. These are almost wholly derived from 
the soil, through the medium of the water absorbed by 
the root-hairs (100). They must all be dissolved in 
the soil water or they cannot enter the plant, for they 
must pass through the cell-walls, which are not perme- 
able to undissolved solid matter. 

6o, The Elements regarded as Essential in the Food 
of Plants are carbon, hydrogen, oxygen, nitrogen, po- 
tassium, calcium, magnesium, phosphorus, iron, chlorin 
and sulfur. Some other elements that do not appear 
essential are also used by plants. All of these elements, 
so far as they serve as food, are absorbed by the plant 
in the condition of chemical compounds, as water, car- 
bonic acid and various nitrates, sulfates, etc. 

6i. The Fart Played by the Different Elements. 
Carbon is the chief constituent of vegetable substances 
and forms about half of their total dry weight. Plants 
obtain their carbon almost wholly from the air, in the 
form of carbonic acid gas, which is a compound of car- 
bon and oxygen. The leaves absorb and decompose this 
gas, retaining the carbon and giving off the oxygen 
(58). Hydrogen and oxygen are obtained by the de- 
composition of water, which is a compound of hydro- 



The Plantlet. 45 

gen and oxygen. These enter into the construction of 
nearly all tissues. Nitrogen is one of the constituents 
of protoplasm (13). Most plants depend upon soluble 
nitrates in the soil for their nitrogen supply, but those 
of the natural order to which the clover belongs* are 
able to appropriate nitrogen from the air (260). Phos- 
phorus and sulfur assist in the formation of albumin- 
ous substances; potassium assists in assimilation (58); 
calciumf and magnesium, while uniformly present, seem 
to be only incidentally useful. Iron is essential to the 
formation of chlorophyll (57). 

Of all the materials obtained by plants from the soil, 
but three, aside from water, viz., nitrogen, phosphorus 
and potassium (253) are needed in such quantities that 
the plants are likely to exhaust the supply, so long as 
water is not deficient. 

62. Water is Necessary to Growth. An adequate 
supply of water is the most important condition for the 
well-being of plants, since it not only serves in nutri- 
tion, but is the vehicle by which all other food con- 
stituents are distributed throughout the plant. Com- 
paratively few soils are so poor as to be incapable of 
producing good crops when sufficiently supplied with 
water, while the richest soils are unproductive when 
inadequately supplied with it. Much of the benefit of 
manuring undoubtedly comes from the increased ca- 
pacity it gives the soil for holding and transmitting 
water (92). 

* Leguminosae. 

t Lime, which is a compound of calcium, appears to be essen- 
tial to the fruiting- of some plants, as the peanut, while detri- 
mental to the fruiting of others, as the cranberry and huckle- 
berry. 



46 Principles of Plant Culture. 

The supplying* of food material is not the only office 
performed by water in the plant. The unfolding and 
expansion of the plantlet is largely due to a strong ab- 
sorptive power for water possessed by the protoplasm 
within the cells. This force causes all living parts of 
plants to be constantly saturated with water. Indeed, 
it distends the elastic cell-walls with water until they 
are like minute inflated bladders. The pressure thus 
set up aids in unfolding the different parts from their 
snug resting-place within the seed-case and enables the 
plantlet to stand erect. Growth by cell division, it is 
true, begins rather early in the germination process, 
but this cannot take place unless the cells are first dis- 
tended with water (29). A sufficient amount of water 
is absolutely necessary, therefore, to growth in plants. 
Foliage wilts in dry weather because the roots are un- 
able to supply enough water to properly distend the 
cells ; growth is impossible in plants of which the foliage 
is wilted. When the water supply is abundant, on the 
other hand, and the absorptive power of the roots is 
stimulated by a warm soil (101), the pressure within 
the cells often becomes sufficient to force water from 
the edges and tips of leaves. The drops of water that 
so often sparkle on foliage in the sunlight of summer 
mornings, commonly mistaken for dew, are usually 
excreted from the leaves. In young plants of the cala- 
dium, water is sometimes ejected from the leaf -tips 
with considerable force. 

The water of plants is almost wholly absorbed by the 
root-hairs (100), the leaves having no power to take up 
water, even in wet weather. The water of plants, with 



The Plantlet. 47 

its dissolved constituents, is commonly called sap, ex- 
cept in fruits, when it is usually called juice. 

63. How Food Materials are Distributed through 
the plant. If we drop a bit of aniline blue into a glass 
of clear water, it will not retain its form and size, but 
infinitely small particles will become detached and move 
about to all parts of the water in which it dissolves. 
This movement vnW not stop until the bit has entirely 
disappeared, and until every part of the water contains 
exactly as much of the aniline blue as every other part. 
This equal distribution of the soluble material takes 
place in response to the law of diffusion, that tends to 
cause any soluble substance to become equally distrib- 
uted throughout the liquid in which it is placed. The 
liquid in the meantime may remain stationary. The 
process would be the same if we were to put in a very 
small quantity of each of several soluble substances at 
the same time. The movements of one of these sub- 
stances would not interfere much with those of the 
others. 

If we could remove some of the dissolved aniline blue 
from the water in one part of the glass, it would follow 
that the dissolved aniline blue would move from the 
other parts toward this point, and if the removal were 
continuous, slow currents would move in this direction 
from all other parts of the glass. 

We may now understand how the materials from 
which the plant is built up are distributed to its dif- 
ferent parts. The water absorbed by the root-hairs 
(100) is not chemically pure, but holds in solution small 
quantities of various soluble matters contained by the 



48 



Principles of Plant Culture. 



soil, some of which are used by the plant in growth. 
As these useful matters are removed from the water of 
the cells, to be formed into food (58), the supply is 
replenished from the soil, not through any power of 
selection possessed by the plant, but in accordance with 
the law of diffusion. In like manner, the food formed 
by the chlorophyll (58) finds its way to the growing 
parts. Soluble matters not used by the plant are not 
taken in to the same extent as those that are needed, 
because their distribution is less disturbed. 

The distribution of soluble matter in the plant is also 
promoted by transpiration (74). 

Section IV. The Inner Structure of the Plantlet. 

Thus far, we have considered the plantlet mainly 
from the outside. Before going farther, it is well to 

learn also something of its 
^c ^Pinner structure. We have 
p^i seen that all parts of the 
plant are made up of cells 
(12) and that these cells dif- 
fer in form and office in the 
different parts. The cells of 
the leaf, for example, are 
different in shape and in the 
use they serve to the plant, 
from those of the stem. 

Fig. 17. Showing- section n -, 

through leaf of Oldenburgh llower Or iruit. 
apple. Ep. epidermis; Pal. , . / / • 

palisade cells; I intercellular 64. The Epidermis (cp -1- 
spaces. Highly magnified. See 

also Figs. 13 and 20. dcr-mis). The plant is cov- 

ered by thin, translucent skin that extends over the 




The Inner Structure of the Plantlet. 49 

entire surface of the leaves, stem and root, called the 
epidermis (Fig. 17 Ep.) This skin is formed of com- 
paratively thick-walled cells and serves to protect the 
more delicate parts within. It may be readily with- 
drawn in some plants, as from the leaves of the live- 
forever* and echeveriat and yonng stems of the plum. 
The exposed surface of the epidermis of the leaves, 
fruit and young stems of many plants is transformed 
into a layer that is more or less impervious to water, 
called the cuticle (cu'-ti-cle), which serves to restrict 
evaporation (74). To further protect the parts, a 
layer of wax (bloom) is sometimes secreted upon the 
outside of the cuticle, as in the fruit of many varieties 
of the plum and grape. 

[Root-hairs (100) and the hairs and bristles on the 
stems and leaves of many plants are cells of the epi- 
dermis elongated outward. The epidermis must not be 
confounded with the bark. It is replaced by bark in 
the older stems of woody perennial plants. 

To give further strength to the upper surface of the 
leaf, the first two or three tiers of cells beneath the epi- 
dermis on the upper side are usually placed endwise, 
{palisade cells, Figs. 17, 15 and 3). The hardier varie- 
ties of apple, as the Oldenburgh (Duchess), have more 
numerous and more crowded palisade cells than less 
hardy varieties. Compare the palisade cells of a leaf 
of the Oldenburgh apple (Fig. 17), with those of Fig. 
3, which shows a section from a leaf of a tender variety 
of apple. 

*Sedum telephium. f CoiyUdon. 



50 Principles of Plant Culture. 

65. Stomata (stom'-a-ta). Minute openings through 
the epidermis occur in the leaves and young stems of 

land plants, 
connecting 
intercellular 
spaces (I, 
Fig. 17) with 
the external 
air. These 
openings are 
each bounded 
by a pair of 
guar d-cells, 
called stom- 
(singu- 
stoma 




Fig. 18. Showing stomata (st.) on leaf of the cita 
garden beet. Moderately magnified. (After Frank ' 

and Tschirch). See also Figs. 15, 19 and 22. 



lar, 

(sto'-ma), Figs. 18 and 19, St). They are chiefly found 
on the lower side of leaves, and are extremely numer- 
ous, but are too small 
to be seen without the 
microscope. An aver- 
age apple leaf has 
been computed to 
contain about 150,000 
stomata to the square 
inch on its lower 
surface. These cells, ^ ,„ „^ . ^ . / ^n ,^ t 

' Fig. 19. Showmg tomato (st.) on leaf 
which are attached "^ Oldenburgh apple. Highly magnified. 

together only at their ends and are thickened on their 
inner side, become bent or crescent-shaped when turgid, 




The Inner Structure of the Flantlet. 51 

thus forming an opening through which water escapes 
and carbonic acid enters the leaf. 

These guard-cells are delicately balanced valves 
which are extremely sensitive to external influences. 
They are open in strong . light, but usually closed in 
darkness and when the leaves are wet. They become 
turgid as the whole leaf is turgid, thus protecting the 
tissues from an excess of water. Conversely, as the leaf 
loses water the guard-cells become less turgid, protect- 
ing the tissues from too great a loss of water. In this 
manner the plant regulates the amount of water in its 
tissues according to its requirements. The slightly- 
raised spots or dots on the smooth bark of the young 
shoots of many woody plants, {lenticels (len'-ti-cels) ), 
serve a similar purpose to the stomata. 

66. The Growing Point. At the tip of the stem 
and just behind the tip of the root, is a group of cells 
forming the so-called g^^owing point. These cells di- 
vide very rapidly during the growing season, and from 
them all other kinds of cells are evolved. 

67. The Vascular (vas'-cu-lar) Bundles.* While the 
plantlet remains within the seed-case, it consists largely 
of cells more or less cubical or globular in outline. But 
germination scarcely commences before some of the 
cells begin to increase greatly in length without a cor- 
responding increase in thickness. f These elongated 
cells form in groups or bundles {vascular bundles) 
that extend lengthwise through the stem and roots, and 

* Also called fibro-vascular bundles. 

t Cells of the former class. 1. e., those that retain their globu- 
lar shape, are called Parenchyma (pa-ren'-chy-ma), and those of 
the latter class prosenchyma (pro-sen'-chy-ma) (Fig. 20). Fig. 17 
shows parenchyma cells from the appple leaf. 



52 



Principles of Plant Culture. 



since the individual cells overlap and are in intimate 
contact, they form threads or fibres. These fibres serve 
the double purpose of giving strength to the plant and 
conducting water, with its dissolved food materials, to 
the different parts. By the absorption of the ends of 
some of the cells, tubes (ducts), of 
very considerable length are formed. 
In other cells of vascular bundles, 
the walls are much thickened and 
strengthened by woody deposits. 
These groups or bundles of fibres 
and ducts divide and subdivide in 
the leaves, forming the so-called 
veins and veinlets. In the roots 
they divide in a similar manner, ex- 
tending lengthwise through all the 
branches and branchlets. 
Fig. 20. Prosenchy- ^ig. 20 shows a longitudinal sec- 
S%ye!"'HSh?5 ma? tion of a vascular bundle of the rye 
and^ Tscmrcho ^'"^''^ plant and Fig. 21 shows a cross-sec- 
tion of a vascular bundle of the sunflower. 

The threads in the stalk of Indian corn and the leaf- 
stem of the plantain* furnish examples of well-defined 
vascular bundles ; in most stems the vascular bundles 
are less clearly defined. In woody stems they are 
closely crowded, which gives the wood its firm texture. 
In some woody plants, as the grape and the elder,! a 
cylinder extending through the center of the stem is 
free from vascular bundles, forming the pith. The 
young stems of asparagus, the ball of the kohl-rabi and 

* Plantago. t Sambucus. 




The Inner Structure of the Plantlet. 



53 




Fig. 21. Showing cross-section of a vas- 
cular bundle of the sunflower. (Helian- 
thus annuus). Highly magnified. (After 
Prantl.) See also Fig. 22. 



the roots of turnip are "stringy" when the cells of 
their vascular bundles become thickened by the de- 
posit of woody ma- 
terial in them. 

68. The Cam- 
bium (cam'-bi-um) 
Layer. In most 
plants having two 
or more cotyle- 
dons (45), a layer 
of cells in a state 
of division (15) 
exists between the 
bark and the wood, 
called the cambium or cambium layer (Fig. 22). It 
is in this layer that growth in diameter oi the stem oc- 
curs (70). The bark of plants having the cambium 
layer separates readily from the wood at times when 
growth is rapid, because the walls of the newly-formed 
cambium cells are extremely thin and tender. The 
slimy surface of growing wood, whence the bark has 
just been removed, is due to the protoplasm from the 
ruptured cambium cells. In plants having more than 
one cotyledon, the cambium line is usually readily dis- 
cerned in cross-sections of the stem — though it is rather 
more distinct and the bark is more readily separable in 
woody than in herbaceous* stems. In the latter, the 
part within the cambium line corresponds to the wood 
of woody stems, and that outside of it corresponds to 
the bark. 



* Herbaceous stems are those that do not have the hard, firm 
texture of wood, as the potato, rhubarb, etc. 



54 



Principles of Plant Culture. 



69. Portions of Cambium from different plants may 
Unite by Growth. If a section of cambium from one 
part of a plant is closely applied to the cambium of an- 
other part of the same plant, or of another closely re- 
lated plant, the two portions of cambium may unite by 




5t-~^... 



c— - 



e— - 



Fig. 22. Showing transverse section of corner of a bean stem 
(Vicia faba). C cambium layer; e epidermis; Cu cuticle; St 
stoma. The dark, oval-shaped spots, extending both sides of the 
cambium layer are the vascular bundles; W wood cells of the 
vascular bundles. Moderately magnified. (After Potter.) 

growth, a fact of great importance in horticulture since 
it renders grafting possible (383). Plants having no 
cambium layer (70) cannot, as a rule, be grafted, be- 
cause their stems have no layer of dividing cells— the 
only cells that unite by growth. 

70. How Stems Increase in Diameter. There is no 
cambium layer in plants having but one cotyledon 
(45), of which Indian corn, the grasses and palms 
are examples. In such plants there is no clear separa- 



The Inner Structure of the Plantlet. 55 

tion between bark and wcod ; the stem enlarges for a 
time by growth throughout its whole diameter, after 
which it ceases to expand. ; 

In plants having two or more cotyledons, however, 
additions to the bark cells are constantly being made 
during the growing season on the outside of the cam- 
bium layer, as are additions to the wood cells on the in- 
side of it (Fig. 22). It follows that growth of the bark 
takes place on its inner surface and growth of the wood 
takes place on its outer surface. This explains the ver- 
tically-furrowed appearance of the bark of old trees 
which is being constantly split during the growing 
season by the forming layer within. It also explains 
the ringed appearance of a cross-section of a woody 
stem. A new ring of wood is formed each season on 
the outside of that previously formed, and the line sep- 
arating the rings marks the point where growth in 
autumn ceased and was renewed the following spring. 
The age of a given part of the stem of a woody plant 
is approximately indicated by the number of its wood 
rings.* 

71. The Vital Part of Woody Stems in plants hav- 
ing more than one cotyledon (45) is limited to a rather 
thin layer of bark and wood, of which the cambium 
(68) forms the center. The cells of the so-called heart- 
wood and those of the dry and furrowed outer bark, 
have lost their protoplasm, and hence are no longer 
alive, though they serve a useful purpose in adding 
strength and protection to the vital layer. The heart- 

* More than one wood ring is sometimes formed in a season. 
If growth ceases during the summer from severe drought or other 
cause, and is renewed the same season, an extra ring is formed. 



56 



Principles of Plant Culture. 



wood of a tree may largely decay without materially 
interfering with the vital processes (Fig. 23). 

72. The Healing of Wounds. Cambium cells ex- 
posed to the air by partial 
or complete removal of the 
bark, soon perish, as a rule, 
hence growth ceases in a 
part of the stem thus in- 
jured. The uninjured cam- 
bium cells on the borders 
of the wound may, however, 
by division (15), form a 
cushion of new material that 
gradually extends over the 
injured part. A new cam- 
bium layer may thus be 
formed over the wound if it 
be not too large, so that 
growth of the stem may be 
resumed at this place. The 
same process occurs when a 
branch is cut off near its 
union with the stem. The 
wound, if not too large, is 
''healed" by new growth 
from the adjacent, uninjured 
cells (Fig. 24). 
The younger the uninjured 
tissues are the more rapid is the healing. In planted 
cuttings, the uninjured cambium cells at the base form 
the callus (cal'-lus) by continued division (Fig. 25). 




Fig. 23. Live poplar tree 
with hollow trunk, showing /^owiViinrvi 
to what extent the heart- camuium 
wood may decay without de 
stroying the life of a tree. 



The Water of Plants and Its Movements. 57 



Exposure of the bark to undue heat or cold may de- 
stroy the cambium, causing sunscald (185). 

In periods of very rapid growth, when the cambium 
cells are unusually active, large areas of bark, even ex- 
tending clear around the stem and as 

deep as the cam- 
bium layer, may 
sometimes be re- 
moved from trees 
without destroy- 
ing their life, pro- 
vided the recently- 
formed wood layer 
is not injured 
(70). In this case, 





Fig 



Healing of 



Fig. 25. Showing 
callus at base of 



wound formed by cu?- the OUtcr CClls of 

ting off a branch (A). ^^^ ^^^.^ j^^^^ ^^ ^.^^^^ ^^...^^ 

cambium that remains on the surface of the wood 
promptly change to bark cells, hence a new bark layer 
forms over the exposed surface the same season. 

Several successive crops of bark are sometimes re- 
moved from the trunk of the cork oak,* but in this 
case, the cambium layer is usually not injured. 

Section V. The Water of Plants and its 
Movements. 

73. Plants Contain Large Amounts of Water. We 

have seen that the cell- walls of living plants are con- 
stantly saturated with water (62), and that the cells of 
the growing parts are always more or less distended 
with it. The proportion of water contained in living 

* Quercuo suber. 
5 



58 Principles of Pla^it Culture. 

plants is generally very large. In the root of the tur- 
nip and in some fruits, it may exceed ninety per cent 
of the whole weight. It is greatest in young plants 
and in the younger and growing parts of older plants. 
The proportion of water is not constant in the same 
plants, but varies somewhat with the water content of 
the soil and with meteorological conditions. 

74. Transpiration (trans-pi-ra'-tion) . The water of 
plants passes off more or less rapidly from parts ex- 
posed to the air— usually as an invisible vapor. This 
invisible escape of water from plants is called trans- 
piration. It is mainly due to evaporation of water 
from the plant, the same as takes place from other moist 
material. But fluctuations occur in the amount of 
transpiration from living plants that do not occur in 
dead organic material under similar conditions. For 
example, transpiration is more rapid in light than in 
darkness, because the stomata (65) are open in the light 
and thus facilitate the escape of water from the inter- 
cellular spaces. Plants poorly supplied with nourish- 
ment transpire more freely under the same conditions 
than those well supplied. The amount of transpiration 
varies greatly in different plants and depends upon the 
leaf surface, the nature of the epidermis and cuticle 
(64), the number of stomata (65), etc. Some plants, 
as purslane, the sedums, cacti, etc., have special water- 
storing tissue, from which transpiration is extremely 
slow. 

Experiments indicate that the transpiration from 
most leaves is between one-third and one-sixth as much 
as the evaporation from an equal area of water. When 



The Water of Plants and Its Movements. 59 

we take into account the immense leaf surface of a large 
tree, it is evident that the aggregate transpiration must 
be very great, as is often illustrated by the dwarfing in- 
fluence of trees upon adjacent crops in dry weather 
(Fig. 26). Transpiration is much more rapid during 










Fig. 26. Showing how a spruce hedge dwarfs an adjacent corn 
crop in dry weather. 

dry than during wet weather, and in the rare atmos- 
phere of high altitudes than in the denser atmosphere 
of low lands. 

Excessive transpiration, as occurs in very dry 
weather, is detrimental to plants, since it reduces the 
water pressure within the cells below the point where 
healthful growth can take place (62) ; but normal 
transpiration, i. e., not sufficient in amount to interfere 
with healthful growth, is doubtless beneficial, since it 
aids in carrying food materials from the soil into the 
leaves (58). For this reason, plants native to regions 
having a rather dry atmosphere, do not thrive in green 
houses unless abundant ventilation is given to encour- 
age transpiration. 

75. Trees are Detrimental to Crops in their vicinity 
not only by the shade they cause, but also by their ex- 
hausting effect upon the soil moisture in dry weather. 



60 Principles of Plant Culture. 

The area affected by a group of trees is often much 
larger than is supposed. Fig. 26 shows how an ever- 
green hedge may restrict the growth of corn in an ad- 
joining field. We should not infer from this, however, 
that trees are on the whole detrimental to agriculture. 
They serve many useful purposes. 

Experimental crops intended to be comparable with 
each other should not be planted near growing trees. 

76. The Brittleness of Young Plant Tissues de- 
pends upon the degree of water pressure within the 
cells. Foliage is usually most brittle during the morn- 
ing and least brittle during the latter part of the day, 
because transpiration is most active during the warm 
hours of the day. Lettuce and other salad plants are, 
therefore, apt to be more crisp and tender when cut 
in the morning. Tobacco, in which breaking of the 
leaves is harmful, is preferably cut in the afternoon. 
Young hoed crops are generally less injured by the 
smoothing harrow in the afternoon than in the morning, 
and grass intended for hay usually dries soonest when 
cut in the afternoon. Lawn grass generally cuts easier 
in the morning than in the afternoon. 

Slightly withered vegetables may have their crispness 
partially restored by soaking them in water for a time. 

77. The Evaporation Current. Since the water of 
plants is taken in from the soil through the root-hairs 
(100), and escapes more or less rapidly by transpiration 
(74), it is clear that in leafy plants a current of water 
must pass from the roots through the stem and branches 
into the leaves, and that the rate of this current will 
depend much upon the rate of transpiration from the 



The Water of Plants and Its Movements. 61 

foliage. When the soil moisture is reduced and trans- 
piration is excessive, this upward current of water is 
not always sufficient to maintain the normal pressure 
within the cells (62), hence the foliage wilts, or the 
leaves roll up, as in Indian corn and some other plants 
of the grass family. This current passes chiefly through 
the younger vascular bundles (67), which in trees con- 
stitute the so-called sap-wood, since the cells of these ' 
are less obstructed by woody deposits than those of 
other tissues. 

The physical forces that cause the soil Avater to rise 
to the tops of tallest trees are not well understood, but 
osmosis^ (os-mo-sis) and the pull produced by the evap- 
oration of water from the leaves, play important parts. 

78. The Flow of Sap in Spring. In the temperate 
zones, evaporation from the leafless stems of deciduous 
trees and shrubs nearly ceases during winter. The por- 
tion of the roots of these plants, however, that lies be- 
low the frost line, continues to absorb water, which 
gradually accumulates in the stems and branches. On 
the return of spring weather, the rise in temperature 
causes expansion of the tissues of the stem, as well as 
of the air and water within it. This creates so much 
pressure in some trees and shrubs that water flows 
freely from wounds in the wood, bearing with it, of 
course, the materials it holds in solution. This hap- 
pens when we tap a sugar maple tree in spring. Alter- 



* Osmosis is the tendency that causes two liquids of different 
densities to mix with each other when separated by a permeable 
membrane. The less dense liquid tends to flow into a denser one 
with a force corresponding to the difference in their densities. 
Cell contents are denser than soil water, hence the latter tends 
to flow into the cells, and thus to rise in the plant. 



62 Principles of Plant Culture. 

nate rise and fall of temperature increases the flow of 
sap, because with each contraction, new supplies of 
water or air are drawn into the stem, and thus the pres- 
sure is maintained. Sap ceases to flow on the opening 
of the buds, because transpiration from the foliage (74) 
quickly relieves the abnormal pressure. 

The popular idea, that the flow of sap in spring is 
due to a rapid rise of water through the stem at that 
season, is erroneous. The sap is really rising through the 
stem much faster in midsummer than in early spring. 

79. The Current of Prepared Food (elaborated sap). 
The food of the protoplasm in the different parts of 
the plant is prepared almost wholly in the leaves (120). 
We know, however, that growth occurs in the stem and 
roots as well as in the leaves. It is clear, therefore, 
that when the stem and roots are growing, a movement 
of food matter must occur from the leaves into these 
organs. This movement may be demonstrated by a 
simple experiment. If a notch deep enough to pass 
through the bark and a little into the wood, is cut into 
the stem of any of our common woody plants during 
spring or summer, a callus or cushion of new cells (72) 
will soon form on the upper side of the notch, but not 
on the lower, showing that the material from which new 
cells are formed is passing downward. Close examina- 
tion will show that this callus forms just outside the 
union of the bark and wood. In all plants having more 
than one cotyledon (45), this current is through the 
sieve tubes in the inner layers of the bark. The pre- 
pared food matter is dissolved in the water that satu- 
rates the cell-walls, and passes from the leaves to other 
parts of the plant by diffusion (63). 



The Water of Plants and its Movements. 63 

80. Killing Trees by Girdling. To destroy the life 
of a tree that can not be conviently removed, we girdle 
it by cutting a notch about the trunk beneath the lowest 
branch. This cuts off the downward food current and 
so starves the protoplasm of the roots. If the notch is 
made after the leaves have expanded in spring, and ex- 
tends only through the bark, the leaves may remain 
fresh for several weeks, for the transpiration current 
passing through the sap-wood (77) may continue. 
Since the roots receive no nourishment, however, they 
will soon cease to grow and will usually die from starva- 
tion before the following spring. If the notch is cut 
deep enough to reach through the sap-wood, thus cut- 
ting off both the ascending and descending currents, 
death of the tree soon follows. 

81. Root Starvation may occur Without Girdling. 
In seasons of extreme drought, when the leaves are 
poorly supplied with crude food materials from the soil, 
the amount of prepared food may be so meagre that 
the food current will be exhausted before it reaches the 
roots. In such cases the roots perish, and the tree is 
found dead the following spring. This most frequently 
occurs w^ith trees on poor soil, that have suffered from 
insect attacks as well as from a dearth of water. It 
often occurs also in recently-transplanted trees that 
fail to make satisfactory growth the first season. 

82. To Destroy the most persistent Weeds we starve 
the roots by preventing all leaf growth (339). 

83. Restriction of the Growth Current Promotes 
Fruitful ness by causing an accumulation of prepared 
food in the stem and branches (134 B). 



64 Principles of Plant Culture. 

84. The Storage of Reserve Food. In healthy 
plants, food is usually prepared faster than it is con- 
sumed by growth. The surplus may be in the form of 
starch, as in the potato (Fig. 16), wheat and sago; 
sugar, as in the sugar cane, sugar maple and beet; or 
oil, as in cotton seed, flax seed and rape. Aside from 
the seeds, which are always stocked with reserve food, 
certain plants living more than one year as the potato, 
beet, onion, kohl-rabi, etc., have special accumulations 
of food in certain parts, and the parts of plants that 
contain such reserve food are most valuable as food for 
man or animals. The proportion of starch stored in 
potato tubers is not constant, hence the food value of 
different samples of potatoes may vary greatly. In 
woody plants, the surplus food is more evenly distrib- 
uted through the different parts, though the older leaf- 
bearing wood is usually best supplied. 

85. Plants Use their Reserve Food in the produc- 
tion of flowers and seeds (134 A) , and in repairing dam- 
ages, as the healing of wounds (72), or the replacement 
of leaves destroyed by insects or otherwise. Annual 
plants (337) expend all their reserve food in flower 
and seed production and then perish as soon as the seed 
is ripe. Biennial plants devote the first season of their 
life to storing an abundant food supply, which is ex- 
pended in flower and seed production the second year. 
Our seed crops, as oats, corn, peas and beans, are mostly 
annuals; our vegetables other than seeds, as beets, cab- 
bage, parsnips and celery, are mostly biennials. Peren- 
nial plants, in normal condition, expend only a part of 
their reserve food in any one season for the production 



The Boot and the Soil. 65 

of flowers and seeds, withholding the remainder for 
nourishment through the winter and to develop leaves 
the following spring. The reserve food in dormant cut- 
tings (358) enables them to form roots and expand 
their buds. 

Section VI. The Koot and the Soil. 

With the out-door cultivator, the part of the plant 
environment that lies beneath the soil surface is more 
under control than the part that lies above it. He can 
do little to change the composition or temperature of 
the air or the amount of sunlight; he may do much to 
influence the fertility, the texture, the drainage and the 
aeration of the soil. A knowledge of the roots of 
plants and of the soil in which they grow and feed, is, 
therefore, of the utmost practical importance. 

86. The Office of the Root. The roots of land plants 
serve (a) to anchor the plant in the soil, enabling the 
stem or stems of erect species to grow upright, and (b) 
to supply the plant with water with its dissolved food 
materials (62). 

87. The Root Originates in the Stem. As we have 
seen, the primary root develops from the lower or 
"root-end" of the hypocotyl (44). But lateral roots 
may develop freely from other parts of the stem. If 
we examine the base of the stem of a plant of Indian 
corn a few weeks after planting, we may see that the 
main roots start above the point at which the stem was 
originally attached to the seed; and if we pull up a 
pumpkin vine or an untrellised tomato plant late in 
summer, we often find it rooted from the stem at some 
distance from the original root. Lateral roots originate 



Q6 Principles of Plant Cultiu^e. 

in the internal tissues of the stem or root and not close 
to the surface, as do buds (131). 

88. Moisture Excites Root Growth. Roots develop, 
as a rule, from portions of the stem that are maintained 
for a certain time in contact with abundant moisture. 
In the pumpkin vine and tomato plant above mentioned, 
nearness to the soil furnishes a moist atmosphere. A 
corn stalk pegged down to the ground for some distance 
will usually root at all joints of the stem in contact with 
the soil. A potato plant grown under a bell- jar, where 
the air is nearly saturated with water, will form roots 
at any joint of the stem. In parts of the tropics where 
the air is very moist, certain plants, as orchids and the 
Banyan tree,* emit roots freely from the stem above 
ground. Cuttings (358) and layers (349) form roots 
because they are maintained in contact with abundant 
moisture and at a suitable temperature. Cuttings of 
some plants, as the willow and nasturtium,t root 
promptly when their stems are immersed in water. 

89. Oxygen is Necessary to the Life of Roots. Since 
the cells of newly-formed roots are filled with proto- 
plasm, they must have access to the oxygen of the air, 
or they can neither live nor grow. This is shown by a 
simple experiment. Boil a quantit}^ of water fifteen 
minutes or longer, to exhaust it of free oxygen, and then 
cool it quickly by setting the dish containing it in cold 
water. Now place a healthy cutting (358) of some 
plant that roots freely in water, as willow, nasturtium 
or wandering jew,| in each of two tumblers. Pour a 

* Ficus Indica. ^ Tropoeolum. % Tradescantia. 



The Root and the Soil. 



67 



part of the cool, boiled water into one of the tumblers 
and add a little olive oil to form a film over the liquid 
thus preventing it from absorbing more air. Then agi- 
tate the rest of the water vigorously to impregnate it 
again with oxygen, and pour some of this into the sec- 
ond tumbler. Set both tumblers in a light, warm place. 
In a few days roots will start freely from the slip in 

the tumbler in which 
the water has access 
to the air, but not in 
the other (Fig. 27). 
If now the rooted 
cutting is placed in 
oil-covered water that 
has been exhausted 
of its oxygen by 
boiling, the roots will 
soon die. 

The copious for- 
mation of root-hairs 
(100) that reach out 
into the moist atmos- 
phere of the seed- 

FiG. 27. Slips of Tradescantia in water 
containing oxygen (left glass) and in tester (38), and that 
water containing no oxygen (right glass). 
From nature. SO oftCU fills the Soil 

cavities with a delicate, cottony down, is further proof 
that roots search for air as well as water. The total 
absence of live rootlets in the puddled clods of badly- 
tilled fields shows that roots will not penetrate soil from 
which the air has been expelled by undue compression 
while wet. Plants in over-watered greenhouse pots 




68 Principles of Plant Culture. 

sometimes send rootlets into the air above the soil to 
secure the oxygen from which their roots have been 
deprived. 

90. The Ideal Soil for Land Plants must contain 
enough i3lant food and water to fully supply the plants, 
and yet be so porous that air can circulate through it 
and come in contact with the roots. Each particle of 
such a soil is surrounded by a thin film of water, while 
between the particles are spaces connected with each 
other, and filled with moist air that is in communica- 
tion with the air above the soil. The root-hairs (100) 
apply themselves intimately to the wet surfaces of the 
soil particles, or reach out into cavities filled with sat- 
urated air, and are thus able to draw in the well-aerated 
soil water, with its dissolved food constituents, in suf- 
ficient quantity to restore the loss from transpiration 
(74) and to distend the newly formed cells (62). 

91. The Soil is a Scene of Constant Changes. The 
part of the soil in which the roots of plants grow is the 
field of most potent vital and chemical activities. The 
dead remains of plants and animals it chances to con- 
tain are undergoing decomposition during the warm 
season, by serving as the feeding ground of myriads 
of microscopic plants (bacteria) (255). Through their 
agency nitric acid, which supplies the higher plants 
with their most valuable food element— nitrogen (254), 
is formed in the soil. The carbonic acid these remains 
took from the air during growth is also set free to 
slowly disintegrate the mineral soil constituents, ren- 
dering these soluble and thus available as plant food. 
In winter, the frost separates the compacted particles 



The Boot and the Soil. 69 

of clods, making the latter permeable to air and root- 
lets, or flakes off new fragments of rock, thus unlock- 
ing new supplies of mineral fertility. 

92. The Importance of Organic Matter in the Soil. 
Crops secure a large part of their nitrogen, as well as 
of other food substances, from dead organic matter, 
i. e., animal or A^egetable materials. The application 
of such matter to the soil is, therefore, of great im- 
portance, where large crops are expected. Stable and 
barn-yard manure, the offal from slaughter-houses, tan- 
neries, breweries, etc., are all valuab^.e for this purpose, 
when wisely used. Stable manure is further beneficial 
by absorbing moisture, oxygen, ammonia and carbonic 
acid from the air as well as much solar heat. Not only 
does organic matter in the soil furnish plant food, but 
while in a partially decomposed state (humus), it ren- 
ders the soil porous and greatly increases its water- 
holding power. 

93. The Soil Needs Ventilation. The roots of grow- 
ing plants and the decomposition of organic matter in 
the soil tend constantly to exhaust the latter of its free 
oxygen, and to replace this with carbonic acid, which 
is not used by the roots. Hence, without some inter- 
change between the contents of the soil cavities and the 
atmosphere above, the roots sooner or later become 
smothered and perish. In sufficiently porous soil, 
changes in temperature and in atmospheric pressure, 
aided by wind and rain, furnish the needed soil ventila- 
tion, but in poorly-drained soils, and soils not thor- 
oughly tilled, the roots of plants often suffer from in- 
sufficient oxygen. A puddled crust on the surface of 



70 Principles of Plant Culture. 

clayey soil, due to the compacting influence of rain, is a 
great hindrance to its ventilation. Earthworms and other 
animals that burrow in the soil aid in aerating it. 

94. Hotbeds Require Especial Care in Ventilation 
(365), since they usually contain large quantities of de- 
composing organic matter (manure), which rapidly ab- 
sorbs oxygen from the soil, replacing it with carbonic 
acid. 

95. Drainage Promotes Soil Aeration by forming 
an outlet for the surplus water that would otherwise 
fill the cavities. Although moisture is essential to root 
growth, land plants do not prosper with their roots im- 
mersed in water. True, most plants may be grown in 
"water culture," i. e., with their roots from germina- 
tion grown in water that is freely exposed to the air; 
but the roots of land plants soon smother for want of 
free oxygen when the soil cavities are filled with water, 
because the soil tends to prevent the water within its 
cavities from absorbing air. 

96. Potted Plants Require Drainage (412) , and the 
outside of the pots should be kept clean, to admit air 
through their walls. Potting soil should contain suffi- 
cient sand and humus (92), so that it does not readily 
become puddled by watering (31). 

97. Potted Plants should be Watered with Care 
(218). They should receive sufficient water so that the 
soil particles are constantly surrounded with a film of 
water, but not so much that the soil cavities remain 
filled. 

98. How the Root-Tip Penetrates the Soil. Darwin 
made the interesting discovery that the root-tip, in ad- 



The Boot and the Soil. 



71 



vancing through the soil, does not move in a straight 
line, but has an oscillating motion, which enables it to 
take advantage of openings between the soil particles. 
The force with which the root-tip is pushed forward was 
calculated by Darwin to be at least a quarter of a pound 
in some cases, while the increase of the root in diameter 
may exert a much greater force. The root-tip is pro- 
tected in its passage through the 
soil by a thimble-like covering 
called the root-cap* 

99. Growth of Roots in Length. 
Since the soil offers more or less 
resistance to the growth of roots, it 
is evident that the roots of land 
plants cannot elongate through their 
whole length at once. On the con- 
trary, the part that increases in 
length is limited to a short portion 
just behind the root-tip. Sachs 
found that the part of the rootlet 
of the broad bean that increased in 
length by growth scarcely exceeded 
Fig. 28. Roots of young half an inch long. In Fig. 28, the 

wheat plant. The parts j_ .t . • . . , 

inclosed in sand (R H) parts that are increasing m length 

are surrounded by 

root-hairs. R T, root- are Considerably shorter than the 

tips; e, older parts of 

root. One-fourth nat- rOOt-tipS (RT). 

ural size. (After Frank 

and Tschirch.) joo. The Root-Hairs (Fig. 29 B) 

develop just behind the elongating part of the rootlet 
and are present in nearly all plants. Their object is to 




* The root-cap is readily seen without a magnifying glass when 
a bean plant is grown in water. 



72 



Principles of Plant Culture. 



absorb water, with the food materials it contains. The 
root-hairs greatly increase the absorbing surface of the 
roots, just as leaves increase the absorbing 
surface of the plant above ground. Each 
root-hair consists of a single elongated 
cell (Fig. 30), and is filled with proto- 
plasm, as are the cells in other living 
parts of the plant (13). As the extrem- 
ity of the root advances through the soil 
by growth, new root-hairs are formed in 
front of the older ones, while those far- 
thest back as rapidly die off, so that only 
a short portion of a rootlet bears root- 
hairs at any one time. In Fig. 27 root- 
hairs are visible in the left glass, and in 

Fig. 29. Seed- ^,. ^ ^ , T / 

lings of turnip Fig. 6 they may be seen on the hpyocotyl 

showing root- 

iiairs. (After of somc of the germinating corn grains. 

Frankand ^ ^ ^ 

Tschirch.) In Fig. 29 A and in Fig. 28 the parts of 

the root bearing root-hairs are indicated by the sand 
which adheres to these parts. It is usually difficult to 
see the root-hairs of plants growing in the natural soil, 





Fig. 30. Magnified root-hair of wheat, in contact with soil 
particles. (After Sachs.) 

but they may sometimes be discovered with the help of 
a pocket magnifying glass by carefully removing the 
soil particles about the younger roots, when the silky 
network of root-hairs may be seen filling the smaller 



The Boot and the Soil. 73 

pores of the soil or enveloping the soil particles. Fig. 
30 shows a magnified root-hair of the wheat plant, 
closely attached to some particles of soil. The root- 
hairs are able to take up water freely, even from soil 
that does not appear very wet, because each soil par- 
ticle is enveloped in a thin layer of water (90). Still 
more interesting is the fact, that root-hairs are able to 
dissolve mineral matters in the soil, by their excretions, 
most important of which is carbonic acid, thus permit- 
ting the plant to use these matters as food. 

loi. Root-Hairs Absorb Water with considerable 
force. It is the absorptive power of the root-hairs that 
causes water (sap) to flow so freely from injured stems 
of grape vines* and some other plants in spring, and 
from wounds in the trunks of some trees in summer. 
This force is probably due to the absorptive power of 
the protoplasm in the very active young root cells. It 
is affected by the temperature of the soil within cer- 
tain limits, lessening as the temperature falls, and in- 
creasing as it rises. Sachs found that the foliage of 
plants of tobacco and pumpkin drooped when the tem- 
perature of the soil in which they were growing was re- 
duced much below 55° F., showing that the roots did 
not absorb enough water at that temperature to com- 
pensate for the loss by transpiration (74). When the 
soil is warm, on the other hand, the absorptive power 
of roots may be sufficient to force water from the tips 
of leaves during cool nights when transpiration is 
slight (62). 

* Hales found the absorbing force of the roots of a grape vine 
equal to the weight of a column of mercury thirty-two and one- 
half inches high. 
6 



74 



Principles of Plant Culture. 



102. Only the Youngest Parts of Roots are Active 
in Absorption. The part from which the root-hairs 
have perished absorbs little water, but is chiefly useful 
in giving strength to the plant and in conducting the 
plant fluids. The absorbing part of any given rootlet 
is, therefore, comparatively short. It follows that the 
amount of nourishment a given plant can receive will 
depend upon the number of its root-tips. Our treat- 
ment of the plant should, therefore, be aimed at pro- 
moting the formation of root-tips. In other words, we 
should encourage root branching.^ How can we do 
this? 

103. The Branching of Roots in land plants appears 
to depend much upon the amount of free oxygen (31) 

and available plant food which 
the soil contains, so long as the 
moisture supply is sufficient. 
In cultivated ground having a 
compact sub-soil the roots of 
annual crops usually branch 
most freely just at the bottom 
of, or a little below, the layer 
of soil stirred by the plow, this 
being the point at which the 
Fig. 31. Showing how Supply of oxygen, plant food 

root pruning stimuates n • . i i i i j. 

root branching. and moisturc are probably best 

suited to root growth. As the depth of tillage is in- 
creased, roots branch freely at a greater depth. Masses 




* Root branches must not be confounded with root-hairs. In 
Fig. 28, branches of the roots appear at e, e. e. The branches 
bear root-hairs when of sufficient length, but root-hairs never 
develop into branches. 



The Root and the Soil. 



75 



of decomposed manure beneath the surface of the soil 
are usually penetrated through and through with finely- 
branched roots; and fragments of bone in the soil are 
often inclosed in a mat of delicate rootlets. These ma- 
terials furnish plant food in abundance. Roots that 
penetrate the deeper and more compact layers of soil, 
on the other hand, and those in poor and dry soils, are 
usually little branched. It is clear, therefore, that un- 
less a soil is well aerated (93) by a proper system of 
tillage, and by draining if need be, and unless it con- 




FiG. 32. Showing- effects of transplanting on root growth of 
celery plants. The left two plants were transplanted when quite 
small; the right two were not. (After Green.) 

tains abundant soluble plant food in the aerated part, 
the roots of plants growing upon it will not branch 
freely and hence the plants cannot be well nourished. 

104. Transplanting (400) and Root Pruning (416) 
Stimulate Root Branching. Removing the growing 
points of either the stem or root (65) stimulates the 



76 Principles of Plant Culture. 

development of other growing points farther back. 
Transplanting or root pruning accomplishes this in the 
case of roots (Fig. 31). While these operations 
may not often increase the total number of root-tips, 
and hence may not enable the plant to take up a greater 
amount of nourishment, they do cause the development 
of a more compact root system, which is of great ad- 
vantage to young plants grown in the seed-bed or nur- 
sery for subsequent transplanting. 

105. Pricking Off Young Seedlings, i. e., transplant- 
ing them from the soil in which they grew to other soil, 
where they have more room, is an important prepara- 
tion for their fmal transplanting. They should receive 
as gocd care after pricking off as before, with which 
they soon develop many new rootlets near the base of 
the stem, that need be little injured in the later re- 
moval (Fig. 32). 

106. Nsirsery Trees are Benefited by Transplanting 
them once or twice before the final planting out, for 
the reasons named above. 

107. Root Pruning (416 k) is sometimes employed as 
a substitute for transplanting, and is especially useful 
to trees that form new branch roots, as the hickory and 
walnut. In this case, the tap root is cut off a few 
inches below the surface of the soil the year before 
transplanting. 

108. The Horizontal Extent of Roots is usually 
greater than is generally supposed. In upright-grow- 
ing plants, the area occupied by the roots, as a rule, 
exceeds that covered by the foliage, while in spreading 
and trailing plants, the roots are probably not often 



The Root and the Soil. 77 

less in extent than the branches. It appears from the 
observations recorded that even in such plants as the 
melon and squash, the horizontal extent of the roots 
usually equals or exceeds that of the runners. As the 
diffusion of soluble matters in the soil water is probably 
much hindered by the soil particles, the roots of plants 
need to travel farther after food than do the branches, 
which develop in a freely circulating medium. Espe- 
cially is this true of plants growing in poor soil. 

109. The Depth of Roots in the Soil. It appears 
from the observations recorded that the extreme depth 
reached by roots is generally less than their greatest 
horizontal extent. The distance reached by the deeper 
roots is probably governed largely by the nature of the 
sub-soil and the depth of free ground water. But in 
most annual crops a comparatively small part of the 
root system develops below the plow line. At the 
Geneva Experiment Station* the chief root-feeding 
ground of the field and garden crops grown in that 
locality appeared to be from three to ten inches below 
the surface, while that of crops making large develop- 
ment of stem and foliage during summer, as Indian 
corn, sorghum, tobacco and the Cucurbitae, appeared to 
be shallower than in slower-growing crops. 

A portion of the roots of many crops grow very near 
the surface of the ground. Branches from the main 
horizontal roots often grow upward as well as in other 
directions. At the Geneva Experiment Station, numer- 
ous roots of sweet corn were found within an inch of 



* See Report of New York Agincultural Experiment Station, 
1886, p. 165. 



Principles of Plant Culture. 



the surface, and in a tall-growing southern corn, roots 
of considerable size started at a depth of only half an 
inch. The main root of a Hubbard squash vine was 
traced a distance of ten feet, in which its depth varied 
from two to five inches. In tobacco fields, the rootlets 
sometimes literally protrude from the surface of the soil 
in warm, wet weather (231). 

no. The Rate of Root Growth in rapidly develop- 
ing plants is often extreme^ fast. President Clark, 
formerly of the Massachusetts Agricultural College, 
concluded from very careful examinations and measure- 
ments of the roots of a 



squash vine grown un- 
der glass, that rootlets 
must have been pro- 
duced at the rate of at 
least one thousand feet 
per day during the lat- 
ter part of the growth 
period. 

III. Relation of 
Roots to Food Supply. 
In the extent of ground 
occupied, root growth is 
relatively less in moist 
and fertile soi's than in 
poorer and drier ones. 

Fig. 33. Young clover plant show- t»ut the rOOtS are prO- 

JSureT''''' ''"' '°°'' ^'^' ^^'^'^portionately more 
branched. In wet seasons, a given plant has less ex- 
tensive root development than in drier seasons, because 




The Stem. 



79 



the roots may then secure the needed food and water 
from a smaller area. Nursery trees grown on fertile 
soils have a more compact root system than those grown 
on poorer soils. 

112. Root Tubercles. Plants belonging to the nat- 
ural order Leguminosae (le-gu-mi-no'-sse), of which the 
clover, pea and bean are familiar examples, when grown 
in ordinary soil have swellings or tubercles on their 
roots (Fig. 33). These are caused by micro-organisms, 
probably of the class known as bacteria, and are of spe- 
cial interest, because 
the organisms pro- 
ducing them render 
nitrogen T>f the air 
available as plant 
food. Plants have no 
power to utilize di- 
rectly the free nitro- 
gen of the air (259). 

Section VII. The 
Stem. 

113. As the root 
develops from the 
base of the hypo- 
cotyl, the plumule, 

Fig. 34. Potato plant. U. St., under- or primary shoot 
ground stems; R, roots. The tubers are 

the thickened distal* ends of the under- (55), dcVclopS from 
ground stems. Much reduced. (After 

Frank and Tschirch.) the Other end and 

becomes, at least for a time, the main axis or stem of 
the plant. 

* See foot note on page 80. 



U.St 




80 



Principles of Plant Culture. 



114. The Stem is, generally speaking, the part of the 
plant that supports the leaves. In exceptional eases, 
as in the potato (Fig. 34) and quack grass, a part of 
the stem grows beneath the ground, on which the leaves 
usually do not develop {underground stems) ; and in a 
few plants, as in some cacti, the stem performs the 
whole office of leaves. The stem may be strong enough 

to support its own weight, as in 

trees and shrubs, or it may de- 

A (\ 111 pend upon other objects for its 

support, as in vines. 

115. Nodes and Internodes. 
Unlike the root, the stem is de- 
veloped in successive sections, 
comparable in part to the stor- 
^'"^ ies of a building. Each section 
or story consists of one or more 
leaves, attached to the distal* 
end of a portion of the stem. 
The part of the stem to which 
the leaf or leaves are attached is 
called a node and the part be- 
low the node, or in the stem as 

Fig. 35. Nodes (N); A, ,1,1 , i . -i 

of the box elder, Negun- a wholc, the part between the 

do aceroides; B, of the . -n ^ ■ , 

wild grape, vitis riparia. nodcs, IS Called an intemode. 

The nodes are distinctly marked in the younger stems 
of most plants by a slight enlargement or by leaf -scars, 
if the leaves have fallen (Fig. 35). The nodes are 
centers of vital activity and are points at which lateral 



N-- 



* Distal means farthest from the point at which growth started. 
It is opposed to proximal, which means nearest the point of origin. 



The Stem. 81 

growing points (buds 127)) are normally formed, and 

whence roots usually start first in cuttings and layerj5 

(358, 349). 
ii6. The Stem Lengthens by Elongation of tlie 

Inter nodes, as well as by the formation of new ones. 

As the internodes soon attain their ultimate length, it 

follows that the stem lengthens only near its distal end. 

An internode that has once ceased elongating does not 
/^ usually resume it, hence the internodes of per- 
ennial plants that are only partly elongated at 
the close of the growing season in general re- 
main undeveloped. When growth is resumed 
in spring, the formation of a comparatively long 
\^ internode beyond the very short ones of au- 
tumn usually forms a perceptible ring about 
the shoot, which enables us to readily locate the 
point at which growth started in the spring 
(Fig. 36). Indeed we can often determine the 
amount of growth that took place during the 
preceding season or even farther back. 
Fig. 36 ny. The Ultimate Length of the Inter- 

Union of ■* ° 

oidTr ^^^ nodes in any plant, or any part of a plant, 
wood. depends upon the rate of growth — rapid 
growth producing long internodes, and vice versa. In 
the same species, therefore, the average length of the 
internodes is much greater in vigorous, young plants 
than in old ones; in the main, central shoot than in 
the branches, and when growth is well started in spring 
than during its decline in autumn. The diameter of 
young internodes that are not unduly shaded is gener- 
ally in proportion to their length, hence rapid'y-grow- 



82 Principles of Plant Culhtre. 

ing shoots are usually thicker than slower-growing ones. 
We can judge of the comparative vigor of nursery 
trees by observing the length and diameter of the 
internodes. 

ii8. The Stem Elongates Fastest just behind the 
growing point (66), and at least in young plants, just 
behind the primary original growing point (55). When 
we desire to check the growth of the stem, therefore, we 
remove the terminal growing point by pinching (416a). 

119. Pinching Stimulates Branching because re- 
moving the terminal growing point stimulates the de- 
velopment of other growing points farther back (104). 

Section VIII. The Leaves. 

We have seen that one or more leaves are normally 
formed at each node of the stem (115). 

120. The Function of Leaves is food preparation 
(58). Since food is prepared only in the light, the 
cells of leaves are in most plants so arranged as to 
best expose them to light, i. e., in thin, more or less 
horizontal plates, which are strengthened and at the 
same time supplied with water by a network of vascu- 
lar bundles (67) connecting with the stem. They are 
protected by the epidermis (64), but have access to 
air through the stomata (65). 

Each leaf, like the stem and root, is developed from 
one or more growing points (66), located near the base. 
Cell division in the leaf is confined to the near vicinity 
of the growing points, hence an injury to the older 
part of the leaf is not repaired further than by the 
formation of callus (72) over the wounded parts. 



The Leaves. 83 

121. The Cultivator Should Provide for Normal 
Leaf Development. Since the protoplasm of the plant 
is nourished by prepared food (58), and since food 
preparation in most plants takes place almost wholly 
in the leaves (120), it is of first importance that the 
plant be so cared for as to promote normal leaf devel- 
opment. Without this, good crops are impossihle. The 
plants must be grown far enough apart so as not to 
unduly shade each other; insects and fungi must not 
be permitted to prey upon them when it is possible to 
prevent it; and the leaves must not be needlessly re- 
moved or injured. The more severe the climate, the 
more important is perfect foliage, because more reserve 
food is required to endure a long, severe winter than 
a short, mild one. 

122. How Far Apart Should Plants be Grown? 
When the finest developed plants, or parts of plants, 
as fruits, flowers, leaves, stems or roots is desired, the 
plants should not be grown so near together as to in- 
terfere with each other's leaf or root development. But 
when the largest crop from a given area is of more 
importance than the development of the individual 
plant, as with grain crops, the loss from a limited 
amount of shade and crowding will be more than made 
up by the increased number of plants. In this case, 
the amount of crowding that will give the maximum 
yield will depend much upon the fertility and moisture 
of the soil, and must generally be determined by ex- 
periment. 

123. Stem and Root Development Depend on the 
Number of Leaves. Since the vascular bundles, through 



84 Principles of Pla^it Culture. 

the formation of which the stem and root increase in 
diameter, originate in the leaves (67), the size and 
firmness of the stem and the root depend somewhat 
upon the number of leaves the plant bears. The more 
leaves it has, the more solar energy it can transform 
into plant tissue. The stem is larger beneath a vigor- 
ous leafy branch, and if cut off some distance above 
a branch, the part thus deprived of its foliage ceases 
to grow, unless it develops new leaves. Trees growing 
in the dense forest, where their lower branches con- 
tinually perish through lack of light, have tall, but 
very slender trunks, and their wood is soft because it 
contains comparatively little fibrous tissue, while other 
trees of the same species in the full light of the open 
field, through the large amount of solar energy ab- 
sorbed by an immense number of leaves, develop mass- 
ive trunks, of which the wood, being packed with 
fibrous tissue, is much stronger than that of the forest 
tree. 

124. The Comparative Size of Leaves on a given 
plant depends much on the water supply during their 
formation. The leaves of sap-sprouts (223), that take 
an undue proportion of water, are usually very large, 
and in upright-growing plants, the leaves on the more 
nearly vertical shoots are usually larger than those on 
the horizontal ones. The more vigorous the plant, the 
larger, as a rule, are its leaves, and the softer is its 
woody tissue. 

In plants grown from seed to secure new varieties, 
large leaves may be taken as evidence of superior root 
development, which implies capacity to endure drought 



The Leaves. 85 

and, therefore, hardiness. In the apple, the large- 
leafed varieties are, as a rnle, hardier than others, prob- 
ably because their vigorous roots supply the needed 
water during the dry season, thus enabling the tree to 
mature healthy wood and buds which can pass severe 
winters unharmed (174). 

Crops grown for their leaves, as cabbage, lettuce, to- 
bacco, etc., are especially liable to be curtailed by 
drought, and hence should be given the culture that 
best promotes soil moisture, as abundant surface tillage 
and liberal manuring (231). 

125. Leaves are usually Short-Lived because they 
become clogged with those mineral matters taken up 
with the soil water which are not used by the plant 
(63) and which do not pass off in transpiration (74). 
In most annual plants (337), the older leaves become 
useless from this clogging and die before the stem is 
fully developed, and in most perennials the leaves en- 
dure but a single season. In the so-called evergreen 
plants, in which the leaves are usually very thick and 
are often well protected against evaporation by a very 
strongly developed cuticle (64), the leaves rarely live 
more than a few years. 

126. The Manorial Valire of Leaves, that mature on 
the plant, is usually small, since the more valuable fer- 
tilizing materials they contain pass into the stem before 
the leaves ripen (170). The mineral matters contained 
in largest quantity by leaves are these that are not 
used by the plant, but have been deposited with them 
during transpiration (125). 




86 Principles of Plant Culture. 

Section IX. The Buds. 

127. The Buds. Each tip of the stem (66) is iu 
most plants protected with a covering of rudimentary 
leaves or leaf-scales, and the tip with its leafy or scaly 
covering constitutes a hiid. A bud forming the apex 
of a shoot is called a terminal bud; one 
at the junction of a leaf with the stem 
(axil) is called an axillary or lateral bud 
(Fig. 37). 

Each bud generally includes one ter- 
minal and several axillary growing points. 
Aside from these, which in the stem exist 
/^^^ only in the bud, a bud is simply a part of 
the stem in which the leaves and inter- 
nodes are in the embryo stage. 
Fig. sT. Buds. ^^ most perennial plants, the rudimen- 
(AftfrBa^r'V'!)' tary leaves that form near the latter end 
of the growing season are changed into hud-scales, which 
serve to protect their growing points from excessive 
moisture and sudden changes in temperature. Axil- 
lary buds which have not yet expanded, are clothed 
with similar scales. Buds inclosed with scales are 
often called winter huds. To more effectually shut out 
water, the scales are coated with a Avaxy or resinous 
layer in some plants, as the horse-chestnut and balm of 
Gilead, and to protect them from too sudden changes 
of temperature, they are lined in other plants, as the 
apple, with a delicate cottony down.* 

* A vertical section of the onion bulb n^ay be used as a mag- 
nified illustration of a bud as it appears in winter, and that of 
a head of cabbage, of a bud unfolding in spring. 




The Buds. 87 

128. Lateral Buds. Nature provides very early 
for the next year's growth in perennial plants. With 
the expansion of each leaf, a bud begins to form at 
its axil, destined if need be to become a branch at a 
later time. Sometimes, however, especially in very 
vigorous shoots, the embryo buds at the axils of the 
earliest formed leaves remain undeveloped. 

129. Branches Develop from Lateral Leaf-Buds 
(131). In trees and shrubs (woody perennials), the 
lateral buds do* not usually push into growth until the 
spring after their formation, unless the terminal bud is 
injured. Indeed, they may never push into growth. 
Some lateral leaf-buds, (131), especially those most 
distant from the terminal bud, usually remain dormant, 
through want of light or nutriment, and are overgrown 
by the enlarging stem the following year. Such over- 
grown buds, stimulated by destruction or injury of the 
stem above, sometimes push into growth years after 
their formation. 

We can usually decide if detached dormant shoots of 
trees and shrubs, as cions and cuttings, are of the pre- 
ceding year's growth or older, since, as a rule, only 
wood formed the preceding year has visible undevel- 
oped buds*. A bud, in pushing into growth, consumes 
reserve food from the parent branch. The more hori- 
zontal a branch the smaller is the supply of water to 
its buds. 

130. Adventitious (ad-ven-ti'-tious) Buds. Although 
buds are normally formed only at the nodes of the 

* Exceptions to this rule are not uncommon in unthrifty trees 
and shrubs. 



88 Principles of Plant Culture. 

stem, they may under the stimulus of unusual root pres- 
sure (101) be formed without regard to nodes. The 
trunk of a vigorous elm, willow or horse-chestnut tree, 
cut off early in the season, often develops a multitude 
of buds from the thickened cambium (68) at the top 
of the stump, and a circle of shoots often spring up 
about the base of a tree of which the top has been in- 
jured by over-pruning or severe cold. Such buds are 
called adventitious. It is, however, often difficult or 
impossible to distinguish between adventitious buds and 
those that have been previously overgrown (129). 

The roots of many plants, as the plum, choke cherry, 
raspberry, etc., develop adventitious buds freely, espe- 
cially when injured, a fact often utilized in propaga- 
tion by root cuttings (376). 

131. Leaf-Buds and Flower-Buds. Buds may con- 
tain only rudimentary leaves, or they may contain rudi- 
mentary flowers, with or without leaves. The former 
are called leaf- or wood-huds, the latter flower- or f^niit- 
huds. Flower-buds are modified leaf-buds. Both origi- 
nate in the cambium layer (68) and are normally 
located at the apex of the stem or in the axil of a 
leaf (127-128). 

132. Flower-Buds are often Readily Distinguished 
from Leaf-Buds by location and appearance the same 
season in which they are formed, which enables the fruit 
grower to anticipate his crop. In the peach and apri- 
cot, and in many varieties of plum, a flower-bud is 
normally formed on each side^ of the leaf-bud in the 
young shoots of bearing trees (Fig. 37). In the apple 
and pear, the flower-buds are less definitely located, 



The Buds. 



89 



but are mostly formed on the short, thick, wrinkled and 
crooked branches from wood three or more years old 
{fruit spurs, Figs. 42 and 43.) In some fruits, as the 
apple, cherry and peach, the flower-buds are usually 
thicker and more rounded than the leaf-buds, especially 
toward spring. Close and persistent observa- 
tion will enable the horticulturist to early dis- 
tinguish the flower-buds in many 
of his perennial plants. 






Fig. 38. 



Fig. 39. 



Fig. 40. 



Fig. 41. 



Fig. 42. 



Fig. 38. Flower-buds of Pottawattamie plum, Prunus angus- 
tifolia. The central bud of each group is a leaf-bud. 

Fig. 39. Fruiting branch of European plum, Prunus domestica, 
B, young wood. A, wood of preceding year. S, fruit spurs. 

Fig. 40. Fruiting branch of Morello cherry, Prunus cerasus. 
B, young wood. A, wood of preceding year. F, clusters of fruit- 
buds. 

Fig. 41. Leaf-buds of the apple. 

Fig. 42. Fruit-bud of apple (F). 

All are reduced one-half. (Figs. 39, 40, 41 and 42 are after 
Barry.) 

In the apple and pear, the buds on the so-called fruit- 
spurs are not necessarily flower-buds, but some seasons 
all are leaf-buds. How early in the life of a bud its 
character is fixed, or if flower-buds ever change to leaf- 

7 



90 



Principles of Plant Culture. 



buds before expanding, does not appear to be known. 
The facts that leafy shoots sometimes grow out of the 
center of flowers, and that petals (142) are sometimes 

developed as leaves, suggest that 
such a change may occur. 

In the grape, flowers appear at 
the first two, three or four nodes 





Fig. 44. Fruit spur of the pear. Re- 
duced one-half. (After Barry.) 

Fig. 43. Fruit spurs of of the young shoots that grow 

the apple. A, points at j, . „ t .-, -,• 

which apples were de- irom stcms lormed the preceding 

tached the preceding 

j^ear; w, wrinkles mark- scasou {canesj and the shoot con- 

ing points at which 

leaves were detached in tinues to O'row bcvond the flowcrs. 
previous years. Re- 
duced. (After Hardy.) The raspberry, blackberry and 

dewberry bloom like the grape, except that the shoots 
terminate in a flower. In the strawberry, the terminal 
bud of the preceding year's growth flowers in early 
spring. In these plants, therefore, the flower-buds are 
enclosed by the same bud scale that inclose the leaf- 
buds, hence, it is more difficult to foresee the number 
of flowers than in the tree fruits. A knowledge of the 
location of the flower-buds is very important in pruning 
plants grown for their flowers or fruits (416). 



The Buds. 91 

133. The Comparative Vigor of Leaf-Buds on a 

given shoot depends somewhat upon their location and 
the length and diameter of the internodes. The ter- 
minal bud, when uninjured, is usually the most vigor- 
ous one, and the vigor of the buds, as a rule, dimin- 
ishes as we recede from the terminal bud. The more 
rapid the growth of the shoot, the less developed, as a 
rule, are the lateral buds. Cions (386) and cuttings 
(358) should not, therefore, be taken from excessively 
vigorous shoots. The more vigorous buds are often ten- 
derer to endure cold than the less vigorous ones, since 
they are usually farther developed the season in which 
they are formed, hence the terminal buds are most often 
injured in winter. 

In the potato tuber, which is the thickened terminus 
of an underground stem (Fig. 34), the most vigorous 
shoot comes from the terminal bud (the so-called seed- 
end) , hence rejecting this part of the tuber in plant- 
ing, as has often been recommended, is detrimental to 
the crop. 

134. Conditions Affecting the Formation of Flower- 
Buds. The majority of cultivated plants are grown 
either for their flow^ers or the product of their flow^ers, 
i. e., fruit or seed. But the flower is not an essential 
part of the plant, and instead of contributing to its 
welfare, as do the leaves and roots, it actually con- 
sumes a part of the plant's reserve food (139). As 
might be expected, therefore, perennial plants do not 
always produce an annual crop of flowers, even when 
well developed in other directions, hence the grower is 
often disappointed. Since flowers can only come from 



92 Principles of Plant Culture. 

flower-buds, a knowledge of the laws that govern the 
formation of these would often be valuable to the cul- 
tivator. Unfortunately, this subject has received less 
attention than is due to it. Two principles may be 
cited, however, which if they do not explain all phe- 
nomena connected with the formation of flower-buds, 
are of sufficient general application to have great eco- 
nomic value, viz. : 

A — Plants form flower-huds only when they contain 
reserve food (84). 

B — A water supply insujfident for rapid growth may 
suffice for abundant food formation (59). 

In support of the first of these propositions, we men- 
tion: (a) Rapidly-growing plants rarely form many 
flower-buds because the food is used up in growth as 
fast as formed, (b) Checking such rapid growth, by 
removing the growing points of the stem or root (67), 
or by withholding water, results in an accumulation of 
food and is often followed by an abundant formation 
of flower-buds, (c) Obstructing the rootward current 
of prepared focd (79), as by "ringing" (416 g) causes 
an accumulation of food above the obstruction and is 
often followed by the formation of flower-buds in that 
part. 

In support of the second proposition we mention: 
(a) Florists often bring their plants into bloom at a 
desired time by withholding water, (b) The flower- 
buds of most out-door plants are formed during the 
drier part of summer,* when a restricted water supply 

* Plants that live over winter and bloom in spring, as the 
apple, strawberry, etc., form their flower-buds the preceding 
season. 



The Buds. 93 

prevents rapid growth, but when abundant sunlight 
and fully-expanded foliage favor food formation (59). 

We may infer, therefore, that treatment that favoy^s 
the accumulation of reser-ve food promotes the forma- 
tion of flower-huds, a proposition that is borne out by 
the experience of practical cultivators. 

135. How can we Promote the Accumulation of 
Reserve Food ? Three general principles may be cited : 

A — Provide for ahundant food formation by giving 
sufficient light and air and by protecting the foliage 
from attacks of insects and fungi (Chap. Ill, Section 
VII). 

B — Provide sufficient plant food in the soil to satisfy 
all requirements of food formation (Chap. Ill, Sec- 
tion VI). 

Q— Provide for a moderate check to growth after the 
proper amount of growth has been secured. 

In the greenhouse where conditions are under con- 
trol, these principles are readily followed, and the 
skilled florist rarely fails to secure bloom at the proper 
time. He gives the desired check to growth by permit- 
ting the roots to become densely matted in the pot {pot- 
hound) , by withholding water, or by pinching the tips 
of the more vigorous shoots. With out-door perennial 
plants, as fruit trees, the problem is more difficult, since 
conditions are less under control than with plants un- 
der glass, but the principle just cited should always be 
kept in mind and carried out so far as possible. 

We can give sufficient light and air by planting the 
trees a sufficient distance apart (122) and by proper 
pruning (Chap. IV, Section III). 



94 Principles of Plant Culture. 

If the soil is properly drained, the natural depletion 
of soil water about midsummer will usually give the 
needed check to growth. In wet seasons, the drying of 
the soil may be promoted by stopping cultivation before 
midsummer and sowing a crop that will increase evap- 
oration from the soil, as oats, clover or buckwheat 
(200). 

136. Pinching Promotes Flowering (416). In cer- 
tain cases, as with seedling trees of which we would 
early know the quality of the fruit, we may give an ab- 
normal check to growth by pinching the tips of the 
young shoots or by root pruning (416 k). These opera- 
tions should be performed early in summer, before the 
period of flower-bud formation, and if the tree is not 
too young, flowers and fruit may be expected the fol- 
lowing season. Frequent transplanting of young trees 
acts like root pruning, especially if the tap-root is sev- 
ered. Such harsh measures, however, while they pro- 
mote early fruiting, doubtless tend to shorten the life 
of trees. 

137. Ringing (415 g) often Causes the Formation of 
Flower-Buds in otherwise barren trees, by obstructing 
the rootward current of prepared food. Twisting a 
small wire about the branch, violently twisting the 
branch itself, or simple bending and fastening it in an 
unnatural position, answers the same purpose. But 
these devices probably weaken the tree and shorten its 
life by robbing the roots of their normal food supply 
and are excusable only in special cases, as with seedling 
trees. It is generally a reproach to the care or knowl- 



The Flower. 95 

edge of the cultivator, if his trees of bearing age cannot 
form flower-buds without such choking. 

Fruit trees grafted on slightly uncongenial stocks 
sometimes flower and fruit more freely for a time than 
when growing on their own roots, because the imperfect 
union of cion and stock (383) forms an obstruction to 
the rootward food-current. 

Section X. The Flower. 

138. The Flower is the developed and expanded 
flower-bud (131). Its office is to provide for the for- 
mation of new plants of its kind (reproduction, (16)). 
Some plants, as the quack grass,* Canada thistlef and 
horseradishi multiply freely in nature without the aid 
of flowers, and nearly all plants may be multiplied in 
culture by other means, but in most of the higher 
plants, the flower is the natural organ of reproduction, 
and the only organ devoted solely to this end. 

139. Flowers Tend to Exhaust the Plant, since they 
are formed from the food prepared by the leaves. But 
since flower-buds are not usually formed until the needs 
of growth are provided for (134 A), the normal pro- 
duction of flowers does not injure the plant. In cer- 
tain cases, however, as ^ in plants weakened by recent 
transplanting or in cuttings (358), flower-buds should 
be removed as soon as discovered, to prevent their ex- 
haustive influence. 

140. The Parts of the Flower. The complete flower 
is composed of four different parts or organs. A knowl- 
edge of these parts is of great importance to the botan- 

* Agropyrum repens. fCnicus arvensis. I Nasturtium Armoracia. 



96 



Principles of Plant Culture. 



Coy-. 



ist in determining species, and also to the plant breeder 
who would practice cross-pollination (151, 440), hence 
we need to consider them in detail. The cherry blos- 
som, of which a vertical section appears in Fig. 45, will 
serve as our first example. 

141. The Calyx (ca'-lyx). Beginning at the bottom, 
the part marked C in the figure is called the calyx. This 
is green in the normal cherry flower. In some plants, 
as the flax, the calyx is composed of several distinct, 

more or less leaf- 
like parts, each of 
which is called a 
sepal (se'-pal). In 
the cherry blos- 
som, the sepals are 
united nearly to 
the top. The calyx 
is usually green, 
but in the tulip and some other flowers it is of another 
color. In the apple and pear, the calyx becomes a 
part of the fruit, and its points are visible in the de- 
pression opposite the stem. 

142. The Corolla (co-roF-la). The more spreading 
part of the cherry blossom, which is normally white 
(Cor., Fig. 45) constitutes the corolla. In the cherry, 
the corolla consists of five distinct parts, only three of 
which appear in the figure, called petals (pet'-als). In 
many plants, as the pumpkin and morning glory, the 
petals are united. In other plants they are united a 
part of the way to the top. The corolla is usually of 
some other color than green. 




Fig. 45. Section of cherry blossom 
calyx; Cor., corolla; Si. stamens. 



The Mower. 97 

143. The Stamens (sta'-mens). Inside the corolla 
is a group of slender organs (S S, Fig. 45), called 
stamens. Each stamen consists of three parts, viz., 
the long and slender portion, connected with the calyx 
below, called the filament (fir-a-ment) ; the swollen part 
at the top, called the anther (an'-ther) ; and the yellow 
dust found upon or within the anther, called the pol- 
len (por-len). Each grain of pollen is a single cell, 
w^hich if fertile (152) contains living protoplasm. The 
pollen is set free at maturity. 

144. The Pistil (pis'-til). The column-like part m 
the center of the flower is called the pistil. This also 
consists of three principal parts, viz., the enlarged flat- 
tened summit, called the stigma (stig'-ma) ; the egg- 
shaped base, called the ovary (o'-va-ry) ; and the slen- 
der part connecting the two, the style. The ovary con- 
tains a smaller, egg-shaped part, called the ovule 
(o'-vule), which when developed becomes the seed. 
Many flowers have more than one pistil, and many ova- 
ries contain more than one ovule. 

Recapitulating, the parts of the flower are, in the 
order we have considered them: 

a — The calyx; when divided, the parts are called 

sepals. 
b — The corolla; when divided, the parts are called 

petals. 
c — The stamens; the parts are the filament, anther 

and pollen. 
d— The pistil or pistils; the parts are the stigma, 

ovary and style. 
The ovary contains the ovule or ovules. 



98 



Principles of Plant Culture. 




145. The Parts of the Flower Vary in Form in dif- 
ferent species. In the pea flower (Fig. 46) the five 

petals, shown 
C^l((/F// separately in 

Fig. 47, are not 
only quite un- 
like the petals 
of the cherry 

FIG. 46. Fig. 47. floWCr, but, aS 

Fig. 46. Flower of the pea, Pisum sativum. „^-.^^„-k,„ +V.,->t- 

(After Baiiion.) appears, tne> 

Fig. 47. The same dissected, showing vari- i-, i 

ation in form of the petals. (After Figurier.) S^re UnilKe eaCll 

other. The stamens (Fig. 48 st.) and the pistil (Fig. 
49) of the pea are also quite different in form from 
those of the cherry. The variety of form in the parts 
of the flowers of different 
species is almost infinite. 

146. Certain Parts of the 
Flower are often Wanting. 
The flowers of the maple 
have no corolla; those of the 
willow have neither calyx nor 
corolla; certain flowers oi 
the pumpkin, Indian corn 
and many other plants have 

Fig 48 Fig 49 

no stamens, while other flow- fig. 48. ' stamens (st)'and 
. . pistil of the pea, Pisum sat- 

ers 01 the same species have ivum. 

Fig. 49. Pistil of the same 
no pistils (153). In many alone. (After Balllon.) 

varieties of the American plums* the pistil is often 
wanting. 

147. Composite (com-pos'-ite) Flowersf are made 

*Prunus Americana, P. angustifolia, P. horlulana. 
t The plants having composite flowers form an extensive family 
in botany, called Compositae. 




The Flower. 



99 




of several individual flowers in the same flower-head. 
The sun-flower (Fig. 50) is a familiar example of a 
composite flower. One of the separate flowers is shown 
in Fig". 51. At the outer edge of the flower-head, is a 
row of individual flowers, each of which has a long, 

yellow, petal-like 
ii^/y^^ appendage (Fig. 
52), called a ray. 
The flowers bear- 
ing rays are called 
ray -flowers. Some 
composite flowers 
as of the tansy* 
are without ray- 
flowers. 

148. The Flow- 
center of the head. ers of the Grass 
Familyf to which the cereals belong, as well as corn, 
sorghum, sugar cane, etc., are quite different from 
those of most other plants. In this family, the flowers 
are arranged in little groups, 
each of w^hich is called a 
spikelet. What we call a 
head of wheat is made up 
of a number of spikelets, 
one of which is shown in 
Fig. 53. Fig. 54 shows the 
spikelet dissected. The two ^^fJ^'^i, 
scale-like parts at the base, 
g. g., are called glumes. The similar pair above, tipped 

* Tanacetum vulgare. f Graminece. 



Fig. 50. Cross-section of flower-head of 
sunflower, Helianthus annuus. Reduced. 
The florets appear closely crowded in the 




Fig. 52. 
Enlarged floret of 
sunflower. 

Fig. 52. Ray-flower of same. 



100 



Principles of Plant Culture. 



with a bristle (the awn or beard) are called the lower 
or outer pales or palets (pa'-lets) or flowering glumes — 
to distinguish them from the smaller and more deli- 
cate upper or inner palets which are just above and 
inclosed within the outer palets. Between the outer 



b^' 





L-'S.. 



,-P 




,b^ 



5V- 



FiG. 53. Fig. 54. Fig. 55. 

Fig. 53. Spikelet of wheat; st, stamens. (After La^aout and 
Dacaisne.) 

Fig. 54. The same dissected; x, axis of spikelet; g. glumes; 
bl, b2, outer pales; Bl, B2, flowers displaced from the axis of 
outer pales; ps, inner pales; a, anthers, f ovary. (After Prantl.) 

Fig. 55. Flower of wheat, enlarged; st, stamens; p, pistil; o, 
ovary. (After LaMaout and Dacaisne.) 

and inner palets are the stamens and pistils, shown 
separately in Fig. 55. 

149. Fecundation (fec'-un-da'-tion) is the union of 
the male and female cell by which the new plantlet is 
formed.* The ovule produces within itself a female 
cell which may be fecundated by the male cell pro- 
duced by the pollen (143). The fecundated cell then 
grows to form a young plant— the embryo (55), and 
the parts of the ovule develop about it, the whole form- 
ing the perfect seed. Unless the ovule is fecundated, 
the seed very rarely develops. A flower that contains 

* The term fertilization (fer-til-i-za'-tion), that has been com- 
monly used for this process, tends to confusion, because this term 
is also applied to the addition of plant food to the soil. 



The Flower. 101 

no pistil and hence no ovule, can of course produce no 
seed. 

150. Pollination (pol-lin-a'-tion), is the access of 
pollen (143), to the stigma (144) — the first step in the 
process of fecundation. During a certain period, the 
surface of the stigma is moistened by the secretion of a 
viscid liquid, to which the pollen grains readily ad- 
here. Fertile pollen grains,* alighting on the stigma 
of sufficiently near-related plants during this period, 
undergo a process comparable to germination, in which 
a slender projection from the pollen cell penetrates 
the stigma, passes lengthwise through the center of the 
style and enters the ovule, where fecundation occurs. 

Pollination is not necessarily followed by fecunda- 
tion. In young plants, and in older plants that are 
lacking in vigor (9), flowers often fail to produce seed 
or fruit, even when pistil and stamens appear to be 
normally developed, and pollination occurs. Pollen is 
probably more profuse and more potent some seasons 
than others. 

In some flowers, as in the pea, the stigma is brought 
into direct contact with the pollen by the elongation of 
the style, but in most plants the pollen must be trans- 
ferred to the stigma by some outside influence, as by in- 
sects, the wind, or gravity. Most flowers which have a 
showy corolla or calyx, or secret nectar, or yield a fra- 
grant perfume, depend largely upon the visits of pol- 
len-loving or nectar-loving insects for pollination. The 
showy parts and the perfume serve as signboards to 
direct the wandering insects to the flowers. Pollination 
is favored by a warm, dry atmosphere. 

* Fertile pollen is pollen that is capable of fecundating female 
cells of its own species. 



102 Principles of Plant Culture. 

151. Cross-Follination occurs when the stigma re- 
ceives pollen from a different plant, especially from a 
plant of a different variety or species (21). The fec- 
undation resulting constitutes a cross or hyhrid, as the 
case may be (23). Cross-pollination is often performed 
artificially (440). 

Close- or self-pollination occurs when the stigma re- 
ceives pollen form its own flower or plant. 

152. Cross-Pollination is Advantageous in plants, 
as Darwin's careful experiments have shown. The 
seeds formed are usually more numerous and larger and 
make more vigorous plants than with close-pollination. 
Especially is this true when the parent plants have 
been subjected to different growth conditions in pre- 
vious generations. Nature favors cross-pollination in 
perfect-flowered plants by numerous adaptations tend- 
ing to prevent self-pollination, as maturing the pollen 
either before or after the receptive stage of the stigma, 
or so locating the stamens that the pollen is not readily 
deposited on the stigma of the same flower.* In some 
cases, pollen is infertile on a stigma of the same flower 
or plant that is abundantly fertile on stigmas of other 
plants of the same species (154), 

153. Perfect, Monoecious (mo-nce'-cious) and Dioe- 
cious (di-oe'cious) Flowers. Flowers containing both 
stamens and pistils (or pistil), as in the apple, tomato, 
cabbage, etc., are called perfect or hermaphrodite (her- 
maph'-ro-dite) ; those containing but one of these or- 
gans, as in the melon, Indian, corn, etc., are called -im- 

* Darwin's work "On the Various Contrivances by which Or- 
chids are Fertilized by Insects" describes many most interesting 
adaptations of this sort. 



The Flower. 103 

perfect or unisexual (ii'-ni-sex'-ual) * Flowers of the 
latter class are called monoecious when the stamen-bear- 
ing (staminate (stam'-i-nate) ) and pistil-bearing {pis- 
tillate (pis'-til-late) ) flowers are both produced on the 
same plant, and dioecious when produced on different 
plants only, as in the hop and date. In a few plants, 
as the strawberry (154) and asparagus, some individu- 
als produce perfect, and some imperfect flowers. 

154. Planting with Reference to Pollination is im- 
portant in certain plants. All dioecious plants (153) 
intended for seed or fruit must have staminate and pis- 
tillate plants growing 
near together or they 
will not be productive. 
The hop plant, persim- 
mon and date palm are 
>.^_^ ^ of this class. 
Fxo.^e" 'imperfect flower" o^J" the The flowers of" many 

"^FiG.^T^'perfect flower of same. ^^ ^ur mOSt productive 

The numerous pistils appear in a ^.^^ip+ip^ ^-P o+rawhprrv 

circular mass at the center, around Varieues 01 SiraWDCriy 

which the stamens are seen in -in Tij_i n 

Fig. 57. yield little or no pollen 

and are unproductive, unless growing near pollen-bear- 
ing sorts (Figs. 56, 57). In many varieties of Ameri- 
can plums and in certain varieties of the pear and 
apple, the pollen, even though produced freely, is in- 
fertile on stigmas of the same variety. To insure fec- 
undation, it is wise to mingle varieties in fruit planta- 
tions rather than to plant large blocks of a single 
variety. 

* The terms hermaphrodite, unisexual and bisexual, though 
often applied to flowers, are inaccurate. 




104 Principles of Plant Culture. 

Section XI. The Fruit and the Seed. 

155. The Fruit, as the term is used in botany, is the 
mature ovary with its contents and adherent parts; it 
may be hard and dry, as in the wheat and bean, or soft 
and pnlpy, as in the apple and melon. But in common 
language the term fruit is limited to the pulpy and 
juicy part of certain plants that contains or supports 
the seed or seeds or that is an after development of the 
flower. To avoid explaining botanical terms, we use 
the word in the latter sense. In this sense, the fruit 
serves the plant by attracting animals that can assist in 
disseminating the seed. 

The seed, as we have seen, is the fecundated and ma- 
ture ovule (144), and its normal office is reproduc- 
tion (16). 

156. The Fruit Rarely Develops Without Fecunda- 
tion of the germ cell of the ovule (149). Varieties of 
the apple and pear have appeared, however, in which 
the pulp develops without seeds. The fruit of the ba- 
nana is almost invariably seedless. The cucumber, grape, 
orange and fig sometimes develop their fruit without 
fecundation of the germ cell. These instances are all 
exceptions to the general rule. 

157. Seed Production Exhausts the Plant far more 
than other plant processes. The seed prepares little 
or no food, while it removes from other parts of the 
plant a comparatively large amount of prepared food, 
which it stores up in a concentrated form as a food sup- 
ply for the embryo (54). Many plants (all annuals 
and biennials) are killed the first time they are permit- 



The Fmit and the Seed. 105 

ted to seed freely, and perennials are often weakened 
by excessive seding.* 

158. Prevention of Seeding Prolongs the Life of 
Plants. Many annual flowering plants, as sweet peas, 
dianthns, etc., that soon perish when permitted to ma- 
ture their seed, continue to bloom throughout the sum- 
mer if the flowers are persistently picked. The yield 
of cucumbers, peas, beans and other garden crops, of 
which the product is gathered immature, may be con- 
siderably increased by preventing the ripening of seed. 

159. Overbearing Should be Prevented. Certain 
varieties of some of our cultivated fruits, as the apple, 
plum and peach, tend to devote an undue amount of 
their reserve food to fruit and seed production in fa- 
vorable seasons, which if permitted, results in enfeeble- 
ment or premature death. The wise cultivator guards 
against this tendency by thinning the fruit before it has 
made much growth, thus saving the tree from undue 
exhaustion and improving the quality of the fruit al- 
loAved to mature. 

Thinning should be done as early as the fruits can 
be properly assorted, and the more imperfect ones 
should always be removed. The proper amount of thin- 
ning will depend upon many conditions, as age and 
vigor of tree, abundance of crop, fertility of soil, water 
supply, etc. It must be determined by judgment and 
experience. Thinning does not increase the total crop 
but it may enhance its value. 

160. The Maturing of Seeds Injures Fodder 
Crops. The food value of straw, from which the ripe 

* Double-flowered varieties of the annual larkspur • {Delphin- 
ium), that bear no seed, have become perennial. 
8 



106 Principles of Plant Culture. 

grain has been threshed, is comparatively small, and 
that of grass and other crops intended for coarse fodder 
is much reduced by permitting the seed to ripen be- 
fore cutting. 

i6i. The Ripening of Fruits. Green fruits assist the 
leaves in food preparation to some extent, but as they 
begin to ripen, the process is reversed. Carbonic acid 
and water are then given off, while oxygen is absorbed. 
Fruits first become sour from the production of acids 
which disappear in part at a later stage, while sugar is 
notably increased. Ripening is favored by warmth and 
in some fruits by light. 

Some fruits, as the strawberry and peach, increase 
rapidly in size during the ripening period, provided 
the water supply is sufficient. 

Color is not always an index of maturity. Blackber- 
ries, currants and certain other fruits improve in edible 
quality for some time after assuming their mature color. 

Most fruits that have attained nearly normal size 
ripen to a degree when detached from the parent plant. 
Pears are usually improved in quality if picked before 
maturity and ripened in-doors. The grape, however, 
fails to develop its sugar if prematurely picked. 

After a certain stage of maturity is reached, all vital 
processes in the pulpy part of the fruit cease, and dis- 
organization (decay) begins, unless prevented by a pre- 
servative process. 

Section XII. The Gathering and Storing of Seeds. 

i6i. The Stage of Maturity at which Seeds will 
Germinate varies greatly in different plants and bears 



The Gathering and Storing of Seeds. 107 

no direct relation to the time at which the seeds are set 
free from the parent plant. Seeds of the tomato will 
germinate when the fruit is little more than half grown, 
and those of the pea will germinate when fit for table 
use. Seeds of the lemon sometimes germinate within 
the fruit. On the other hand, seeds of the thorn* and 
juniper rarely germinate until the second spring after 
their production. Seeds of many annual and biennial 
plants, as the cereals, cabbage, etc., may germinate as 
soon as set free by the parent plant, but those of many 
annual weeds and of most trees and shrubs will not 
germinate until some months afterward. 

Seeds necessarily gathered immature will often ripen 
sufficiently for germination if a considerable part of 
the plant is plucked and cured with them. 

Germinating seeds in which the germination process 
is stopped by undue drying are not always destroyed. 
Germination may be resumed on access to water. Seeds 
of different species differ widely in this respect. Those 
of the parsnip and carrot cannot endure much drying 
during germination, while those of the ce-reals may be 
repeatedly dried at ordinary temperatures without de- 
stroying their vitality. 

163. Immature versus Ripe Seeds. Seeds not fully 
grown lack a part of their normal food supply, and 
their embryo is probably imperfectly developed. If 
capable of germination, they rarely produce vigorous 
plants. As a rule, the most vigorous plants come from 
f idly -matured seeds. Immature seeds, persistently used, 
may tend to reduced vigor, early maturity, dwarfness 

* Crataegus. 



108 



Principles of Plant Culture. 



and shortened life. In some over-vigorous plants, as the 
tomato, slightly immature seed may tend to increased 
fruitfulness. 

Slightly immature seeds usually germinate sooner 
than fully matured ones. 

164. The Vitality of all Seeds is Limited by Age, 
but the duration of the vital period varies greatly in 
different species. Seeds of the chervil rarely germinate 
if much more, than one year old, while those of the 
gourd family, the tomato and celery often germinate 
well when ten years old. As a rule, oily seeds, as of In- 
dian corn, sunflower and the cabbage family (cabbage, 
cauliflower, kohl-rabi, Brussels sprouts, ruta-baga, rape, 
turnip, mustard) are shorter lived than starchy seeds, 
as wheat and rice. Oily seeds cannot safely be stored 
in bulk in large quantities, except in cool weather. The 
following table gives the average period during which 
the seeds named are reliable for germination, when 
properly cared for:* 



Duration of 
Germinating Power. 

Average. Exlreme. 
Years. Years. 

10 



Artichoke 6 

Asparagus 5 

Bean 6 

Bean — Kidney 3 

Bean — Soy 2 

Beet 6 

Borecole or Kale 5 

Broccoli 5 

Cabbage 5 

Cardoon 7 

Carrot 4 or 5 

Cauliflower 5 

Celery 8 10 

Chervil 2 or 3 6 

Chervil — Sweet-scented . 1 

Chervil — Turnip-rooted . 1 

Corn Salad 5 

Cress — American 3 

Cress — Common Garden. 5 

Cress — Water 5 

Cucumber — Common .... 10 10 

Eggplant 6 10 

Endive 10 10 



Duration of 
Germinating Power. 

Av. Ext'm. 
Yrs Yrs, 

Gumbo or Okra 5 10 

Hop 2 4 

Kohl-Rabi 5 

Leek 3 

Lentils 4 

Lettuce 5 

Maize or Indian corn.... 2 

Melon — Musk 5 

Melon— Water 6 10 

Mustard — Black or Br'n. 4 9 

Onion 2 

Parsnip 2 

Parsley 3 

Pea 3 

Pumpkin 6 

Rhubarb 3 

Salsify 2 

Sea-kale 1 

Spinach — Prickly-seeded . 5 

Squash 6 

Strawberry 3 

Tomato 4 

Turnip 5 



10 
9 
9 
9 

7 
10 



7 
4 
9 
8 

10 
8 
8 
7 
7 

10 
6 
9 

10 



* From "The Vegetable Garden," Vilmorin. Andrieux & Cie, 
Paris. 



The Gathering and Storing of Seeds. 109 

165. Conditions Affecting the Duration of Seed 

Vitality. A uniform degree of humidity and tempera- 
ture tends to prolong the vital period of seeds by caus- 
ing little drain upon the life of the living cells. Seeds 
deeply buried in the ground are often capable of ger- 
mination at a great age, and kidney beans at least one 
hundred years old, taken from an herbarium, are said 
to have germinated. In these cases, the seeds were sub- 
jected to few variations in humidity and temperature. 
Seeds usually retain vitality longer when not re- 
moved from their natural covering, probably because 
they are thus exposed to fewer changes of humidity 
and temperature. Timothy seeds, that became hulled in 
threshing, lose vitality sooner than those that escape 
hulling, even when the two sorts have been kept in the 
same bag. Indian corn is said to retain vitality longer 
on the cob than shelled, and longer when the ear is 
unhusked than if husked. 

166. Moisture is an Enemy to Stored Seeds, except 
for the class that requires stratification (169). A little 
moisture in stored seeds is very liable to cause the de- 
velopment of fungi (moulds) that may destroy the em- 
bryo. Damp seeds are also liable to be destroyed by 
freezing. It is important that seeds he dried promptly 
after gathering, for if mould once starts, subsequent 
drying may not destroy the fungus; the latter may re- 
sume growth as soon as the seed is planted, thus en- 
feebling or destroying the embryo before it has time 
to germinate. Drying by moderate artificial heat (not 
higher than 100° F.) is wise with seeds gathered in cold 
or damp weather. 



110 Principles of Plant Culture . 

Seeds are shorter-lived in warm than in cooler cli- 
mates. 

The most satisfactory method of preserving seeds in 
quantity is to inclose them in bags of rather loose tex- 
ture and of moderate size, and to store them in a cool, 
dry and airy place. 

167. Age of Seed as Affecting the resulting Crop. 
Seeds grown the same or the preceding season produce, 
as a rule, more vigorous plants than older seeds. They 
may not, however, in all cases produce plants that are 
nxost productive of fruit or seed, for excessive vigor is 
generally opposed to reproduction. Cucumber and 
melon plants grown from seed three or four years old 
are often more fruitful than those from fresh seeds. 
In crops grown foreparts other than fruit or seed, fresh 
seeds are undoubtedly preferable, but in crops grown 
for seed or fruit, fresh seed may not always give as 
large returns as seed of some age. This subject needs 
further investigation. 

168. How Drying Affects the Vitality of Seeds. 
The vigor of seeds is probably never increased by dry- 
ing them, but the seeds of most annual and biennial 
plants may become air-dry without material loss of 
vitality. The seeds of many shrubs and trees, however, 
lose vitality rapidly by such drying and those of some 
species are destroyed by it. In nature, seeds of the 
latter class are usually dropped from the parent plant 
before becoming dry and are soon covered by leaves or 
other litter that keeps them moist. Nurserymen either 
plant such seeds as scon as they are ripe, or if of spe- 



Decline of Growth and the Rest Period. Ill 

cies that do not germinate as soon as ripe, they imitate 
nature by the process known as 

169. Stratification of Seeds. This consists in mix- 
ing the freshly-gathered seeds with sand, taking care 
that the sand is kept moist until the time for sowing 
arrives. Large quantities of seeds may be stratified in 
boxes, by placing the moist sand and seeds in alternate 
layers, cr the layers may be built up in a pile on the 
ground. The sand should be coarse enough to admit 
some passage of air between the particles and to give 
perfect drainage. The layers should not much exceed 
an inch in thickness, except for the larger seeds, and the 
number of layers should not be so large as to prevent 
proper aeration of the mass. Small quantities of seeds 
may be mixed with sand or porous loam in flower-pots. 
Moisture may be maintained in the boxes or pots by 
burying them a foot or more deep in the soil in a well- 
drained place, or by storing them in a moist cellar. 
Care is necessary to keep mice and other vermin from 
stratified seeds. It is well to cover pots in which valu- 
able seeds are stratified, with a sheet of tin or zinc; 
metal labels are best for distinguishing different sorts 
of seed. The seeds should remain stratified until sow- 
ing time, when they may be sifted out of the sand or 
sown with it, as is more convenient. Seeds that do not 
germinate well until the second spring after maturity 
(162) are commonly left in stratification until that time. 

Section XIII. The Decline of Growth and the 

Rest Period. 

170. Annual plants usually perish soon after matur- 
ing their seed. In other plants, a certain period of 



112 Principles of Plant Culture. 

vital activity is followed by one in which growth gradu- 
ally decMnes until it almost or entirely ceases. In 
woody plants, the cells become thickened and a part 
of the rudimentary leaves change to bud-scales, which 
inclose the growing point (127). In deciduous (de- 
cid'-u-ous)* trees and shrubs, the chlorophyll and 
starch, with most of the potash and phosphoric acid 
contained in the leaves are withdrawn into the woody 
parts (126), while the leaves themselves are detached and 
fall. The root-hairs also die in many, if not all plants. 
The leaves of many trees and shrubs assume striking 
colors as they approach maturity. In perennial herbs, 
the nutritive matters in the foliage and stem are with- 
drawn to the underground parts. A period of almost 
complete repose, ensues, during which the plant, owing 
to the dormant condition of its protoplasm, is able to 
endure without harm extremes of temperatures or dry- 
ness that would be fatal in its active state. 

Growth ceases in many trees and shrubs earlier 
than is often supposed. Most orchard and forest trees 
of mature age grow little, if any, after midsummer in 
the temperate zones. Cultivation, mulching, manuring 
and wet weather tend to prolong the growth period 
(199).. 

171. The Rest Period is Not Peculiar to the Tem- 
perate Zones, but occurs in the tropics as well. It can 
be ascribed in part to the change of seasons, as a few 
familiar examples will indicate. Tubers of the earlier 
varieties of the potato, that ripen in northern countries 

* Deciduous trees and shrubs are those of which the leaves 
perish at the beginning- of the rest period. 



Decline of Growth and the Best Period. 113 

by the beginning of August, do not sprout if left in 
the ground till October, but if stored in a cellar during 
winter at a temperature little above freezing, they 
often begin to sprout in March. Bulbs of the crocus, 
tulip, narcissus, crown imperial, etc., that form in 
spring, lie dormant in the warm soil during summer 
and early autumn, but start vigorously in the colder 
soil of the late autumn or the succeeding spring. The 
buds of many trees, that form in summer for the next 
year's foliage and flowers, remain dormant during the 
hot weather of August and September, to push vigor- 
ously in the first warm days of spring. The rest period 
is to be regarded as a normal, if not a necessary factor 
of plant life. 

172. Most Plants Under Glass Require Rest from 
time to time, or they do not thrive. The rest is pro- 
vided either by keeping them at a lower temperature 
than is favorable to growth, or bj^ submitting them to a 
degree of dryness that prevents growth. The latter is 
preferable for plants native in the tropics, where they 
naturally lie dormant during the dry season. 

173. The Time of Leaf Fall is an Index of Wood 
Maturity in healthy deciduous trees and shrubs. lu 
these, the coloring and fall of the leaves. in autumn is 
not necessarily due to frost, but results from the dor- 
mant condition that accompanies maturity. As a rule, 
the more mature leaves are precipitated by the first au- 
tumn frost. Those less mature usually remain until 
the more severe frosts. In trees with well-ripened 
wood, the leaves at the tip of the shoots usually fall 
before, or not later than, these en the older parts of 



114 Principles of Plant Culture. 

the tree. With poorly-matured wood the reverse is the 
case. In a few deciduous trees, as the beech and some 
oaks, many of the mature leaves remain on through the 
winter. 

174. Hardiness Depends upon the Degree to which 
the Dormant State is Assumed. Since the most se- 
vere climatic extremes come during the natural rest 
period of plants the ability of the plant to endure these 
extremes depends upon the extent to which the pro- 
toplasm becomes dormant during the decline of growth. 
As a rule, a given plant is hardy (10) in a locality 
in which the duration and the warmth of the growing 
season are sufficient to complete and fully mature its 
normal amount of growth. Varieties of the apple and 
other trees, that so far complete their growth in any 
given locality that their leaves fall before hard frosts, 
are rarely injured in winter, while those that continue 
growth until their foliage is destroyed by freezing suf- 
fer in severe winters. Deciduous trees are liable to 
destruction in severe winters in a climate where none of 
the leaves fall before hard frosts, as is the case with 
the peach, apricot and nectarine in northen United 
States. 

175. Individual Plants Cannot Adjust Themselves 
to a New Environment, except to a slight extent. The 
power to complete the annual growth processes and be- 
come sufficiently dormant to endure the rigor of the 
rest period in any given locality is inherited, and not 
acquired. We are, therefore, able to do very little 
toward inuring or acclimatizing (ac-cli'-ma-tiz-ing) in- 
dividual plants to an environment to which they were 



Decline of Groivtli and the Best Period. 115 

not adapted by nature. We may, however, through the 
variations of offspring (18), secure varieties in some 
cases that can endure an environment which the parents 
could not endure. 

176. Plant Processes during the Rest Period may 
not entirely cease. Although food preparation is wholly 
suspended, root growth and the callusing (72) of in- 
jured root surfaces proceed to some extent during win- 
ter in unfrozen layers of soil; and in sufficiently mild 
weather, the reserve food in the stem gradually moves 
in the direction of the terminal buds. 

177. Cuttings (358) of Woody Plants are Prefer- 
ably Made in Autumn in climates of severe winters 
and buried in the ground below the limit of hard freez- 
ing, in order that callusing (72) and the transfer of 
food may make some progress before the final planting. 

178. The "Turn of the Year." Toward the close of 
the dormant season, vegetation, as if benefited by the 
rest, is prepared to start with renewed vigor, even at 
moderate temperatures. Buds, that remained dormant 
during the latter part of the previous summer, push 
into growth with the first warm days of spring, and 
many seeds, that could not be induced to germinate the 
preceding autumn, start with vigor as soon as the soil 
is sufficiently w^arm. 

The cause for this energetic resumption of plant 
growth after the rest period is not well understood, 
but exposure to cold, in the case of temperate plants, 
and to prolonged dryness in that of tropical ones, 
doubtless explains it in part, for it is well known that 
potato tubers may be induced to start their buds soon 



116 Principles of Plant Culture. 

after maturity by exposing them to the sun a few days, 
or by placing them for a like time in a refrigerator 
containing ice. By these means, the farmers of Ten- 
nessee grow a second crop of potatoes in the latter part 
of summer and during autumn. 

Plants under glass usually thrive better after mid- 
winter than before, and the most favorable time to 
plant seeds of greenhouse plants is toward the close of 
the natural rest period. 

179. The Round of Plant Life has now been traced, 
from the first swelling of the planted seed, through the 
development of the embryo into the plantlet, the pene- 
tration of the root into the dark and damp soil cavities, 
the absorption and conduction of water with its food 
materials in solution, co-operating with the sunlight 
and carbonic acid in the mysterious laboratory of the 
leaf, in building up the plant body into node and inter- 
node, leaf, bud, branch, flower, fruit and seed; through 
growth decline, leaf fall and winter sleep, to the re- 
newed vigor of another springtime. 

In our study of the round of plant life, we have as- 
sumed the environment to be favorable. But in the 
practical culture of plants, we are constantly meeting 
with adverse conditions of environment. Talent for 
plant culture lies in the ability to discern these adverse 
conditions by the appearance of the plant, and in know- 
ing how to correct them. We will, therefore, next con- 
sider the plant as affected by unfavorable conditions of 
environment. 



Decline of Growth and the Rest Period. 117 

The following books are recommended for reading in 
connection with the preceding chapter: How Plants 
Grow, Gray; Lessons in Botany, Gray; Botanical Text- 
Book, Gray; A Treatise on the Physiology of Plants, 
Soraner; The Soil, King; The Fertility of the Land, 
;Roberts. 



CHAPTER III. 

THE PLANT AS AFFECTED BY UNFAVORABLE 
ENVIRONMENT. 

i8o. Factors of Environment. The plant environ- 
ment is mostly comprehended by the terms, climate, 
soil, animals and other plants. But as these are more 
or less complex influences, it is well to analyze them 
and to consider separately the component factors of 
each. 

Section I. The Plant as Affected by Unfavorablt] 

Temperature. 

A— The Plant as Affected by Excessive Heat. 

i8i. Transpiration Increases with the Degree of 

Heat. The most common effect of heat upon plants is 
the drooping of the foliage, due to excessive transpira- 
tion (74). With insufficient water, this may occur at 
a temperature that is normal for the plant. But with 
a water supply that is sufficient at ordinary tempera- 
tures, transpiration may be so much increased by an 
overheated atmosphere that the roots are unable to sup- 
ply the plant with sufficient water, hence the cells be- 
come partially emptied and the foliage droops. Her- 
baceous plants in an overheated greenhouse or hotbed 
are sometimes so prostrated from excessive loss of water 
as to appear dead, but unless the heat has been suffi- 
cient to destroy their protoplasm, or the heated period 
has been protracted, they will recover when normal 
temperature and water supply are restored. 



Plants as Affected by Heat. 119 

182. Evergreen Trees are sometimes Destroyed by 
Untimely Warm Weather in spring. "With a soil so 
cool that the roots are inactive, a sudden rise of atmos- 
pheric temperature, especially if accompanied by a dry- 
ing wind, may so far reduce the water in the leaves of 
evergreen trees as to cause death of the foliage and even 
of the trees themselves. This most frequently happens 
in the seed-bed, in compact nursery plantations, or 
with recently transplanted evergreen trees. It is most 
disastrous on poorly-drained clay soils that have a sunny 
exposure, and at times when the ground is deeply frozen. 

The preventives to be observed are, a, means that 
favor prompt thawing of the ground, as thorough drain- 
age and not too close planting; h, means that prevent, 
in a measure, exposure to the sun, as planting on a 
northern slope or shading the trees (414) ; c, means 
that tend to prevent deep freezing of the soil, as. pro- 
viding wind breaks which tend to retain the snow (203). 

183. A Temperature of 122° F. is Fatal to the Pro- 
toplasm of most land plants. Aquatic plants and the 
more watery parts of land plants perish at a somewhat 
lower temperature. Watery fruits, as tomatoes and 
gooseberries, and the younger leaves of deciduous trees, 
are sometimes destroyed by exposure to the sun's rays 
in hot weather. An occasional sprinkling of the plants 
and of the soil about them will usually prevent this 
result. 

184. Plants Under Glass should Not be Sprinkled 
in Bright Sunshine. Drops of water upon the leaves 
of plants often act as lenses in converging the rays of 
the sun, and in a closed greenhouse or hotbed may cause 



120 



Principles of Plant Culture. 



a heat that is fatal to the foliage beneath them. This 
may explain the brown spots so often observed upon the 

leaves of indoor plants that 
have been sprinkled in bright 
sunlight. Sometimes, but rare- 
ly, this trouble occurs in the 
open air. 

185. Sun-Scald is the term 
applied to an affection of the 
trunk and larger branches of 
certain not cpiite hardy trees, 
usually upon the south or 
southwest side, in which the 
bark and cambium layer (68) 
are more or less injured (Fig. 
58). In severe cases, the cam- 
bium is totally destroyed, and 
the loosened bark splits longi- 
tudinally or becomes detached. 
The effect is apparently the 
same as when a tree is exposed 
to the heat of a fire. Sun-scaid 
is most common in young trees, 
especially in those recently 
transplanted or overpruned. 
It appears to be due, in some 

Fig. 58. Showing effects of , ,i i -• £ 

sun-scald on trunk and cascs, to the Superheating 01 

branches of silver maple ... 

tree, Acer dasycarpum. the camblUm in SUmmer — 111 

others to a return of severe freezing weather after a 
period sufficiently warm to excite the cambium cells to 
activity. A. preventive is to shade the trunk and larger 




Plants as Affected hy Cold. 



121 



branches by inclosing them with straw or similar ma- 
terial, or with a lath screen (Fig. 59). 

i86. Potato Foliage is often Injured by Sun Heat in 

summer, as is shown by the browning of the leaves from 

the tip and edges toward the cen- 
jy ter, or on the border of holes made 
by insects. This affection, known 
as tip-hum, is due to the destruc- 
tion of protoplasm in the cells and 
is often mistaken for fungus work. 
It is most serious in dry seasons. No 
remedy for it is known, but it may 
be in part avoided by selecting va- 
rieties least subject to it. 

B— The Plant as Affected by 
Excessive Cold. 

187. The Immediate Effect of 
Cooling the Plant is to check the 
activity of its vital processes. When 
a certain degree of cold is reached, 
the protoplasm loses its power to 
imbibe water (62) ; hence the plant 
• \ ' n^M f tissues become less turgid, and the 
SlIi^^^Mi'M foliage droops somewhat (102). 
' "With a sufficient reduction of tem- 
FiG 59. Trunk of ap- perature, ice crystals form within 

pie tree inclosed in ^ ' *^ 

lath screen. ^j^g tissues and the succulent parts 

of the plant assume a glassy appearance. The foliage 
of many plants, as celery, parsnip, etc., assumes an 

abnormal position when frozen. 

9 




122 Principles of Plant Culture. 

i88. The More Water Plant Tissues Contain, th(3 
Sooner they Freeze. Since the water of plants is not 
pure, but is a solution of various substances, it dees 
not freeze at the freezing point of pure water (32^ 
F.), but at a lower temperature, determined by the de- 
gree of concentration of the solution, or the intimacy 
with which it is combined with the tissues of the plant. 
The more thoroughly dormant the condition of a plant, 
or part of a plant, the less water does it contain, and 
the better is it able to endure cold (174). 

189. The Power of Plants to Endure Cold depends 
upon various conditions, aside from the amount of 
water contained, as 

a— Heredity. Plants by nature possess widely differ- 
ing powers to endure cold. The Anoectochilus (a-noec'- 
to-chi'-lus) perishes when exposed for a considerable 
time to a temperature of 42° F., while other plants, as 
the common chickweed,* are uninjured by prolonged 
cold, far below the freezing point (175). 

b — The rate of thawing of the frozen tissues. The 
more slowly the thawing takes place, the less likely is 
the frozen part to suffer injury. Many bulbs, tubers 
and roots which survive the severest winters within the 
soil, where they thaw slowly, are destroyed by moderate 
freezing if quickly thawed. Frost-bitten plants are sel- 
dom injured when sheltered from the morning sun by 
a dense fog, which causes them to thaw slowly. Apples, 
covered in the orchard in autumn by leaves, sometimes 
pass a severe winter with little harm. 

* Stellaria media. 



Plants as Affected hy Cold. 123 

When the water that is withdrawn from the tissues 
in the freezing process is gradually set free by slow 
tha\'^dng, it may be absorbed by them again and little or 
no harm results. 

c—The length of time the tissues remain frozen. A 
comparatively slight degree of frost, if prolonged, may 
act more injuriously than a severer degree of shorter 
duration. Prolonged freezing is especially injurious 
when the frozen parts are subjected to drying wind, 
which evaporates their water, while the frozen condi- 
tion prevents movements of their fluids. 

6.— The frequency with which freezing and thawing 
are repeated. Frequent slight freezing and thawing 
are far more injurious than a prolonged frozen condi- 
tion, even though the latter occurs at a much lower tem- 
perature. Winter wheat and rye, and strawberry beds 
are often more damaged in mild winters, in which freez- 
ing and thawing weather alternate, than in more severe 
ones, when the temperature is mostly below freezing. 
The chief damage is usually dene to these crops in late 
autumn and early spring. 

e — The previous treatment of the plant. Plants grown 
by artificial heat may be far less able to endure cold 
than others of the same varieties grown in the open air, 
possibly owing to the more succulent condition of the 
former. Gardeners harden plants grown under glass, 
by gradually exposing them to the cooler out-door at- 
mosphere, before removing them to the open ground. 

I— The treatment of the frozen tissues. Handling 
plants, fruits or vegetables while frozen greatly aggra- 
vates the damage from frost, probably because the han- 



124 Principles of Plant Culture. 

dling increases laceration of the cells by the ice crystals 
within them. 

190. Frost-Injured Plants, Fruits or Roots May 
often Be Saved from serious damage, if promptly 
placed under conditions that cause the slowest possible 
thawing of the tissues, as shading from the sun's rays, 
immersing in ice water or covering with snow. They 
should he handled as little and as car ef idly as possible 
while frozen. Sprinkling with cold water is often suf- 
ficient to restore frost-bitten plants. 

Aside from the death of tender plants by cold, more 
or less hardy species suffer injur}^ in a variety of ways, 
of which the following are examples : 

191. Destruction of Terminal Buds by Cold. In 
plants which do not mature their terminal buds in au- 
tumn, as the raspberry, sumac, grape, etc., destruction 
of the tips of growing shoots by frost is a regular oc- 
currence in climates of severe winters. The distance 
which the shoots are killed back depends upon the suc- 
culency of the growth, the severity of the winter and 
the natural power of the plant to endure cold. Plants 
thus affected are not always to be regarded as tender, 
since they often grow wild in climates of very severe 
winters. 

192. The Darkening of the Wood (hlack-heart) of 
certain trees, as the pear, in climates of severe winters, 
appears to be a chemical effect of the cold. It begins 
at the center of the stem and in extreme cases may ex- 
tend clear to the cambium, when the bark ceases to 
adhere, and the tree or branch thus affected dies. In 
stone fruits, this trouble is often accompanied by a 



• Plants as Affected hy Cold. 125 

flow of gum. If the coloring of the wood does not ex- 
tend to the cambium, the tree or branch may survive, 
but the first season's growth thereafter is generally 
feeble and the fruit or the seed .crop often fails. Dur- 
ing the second season, healthy growth may be resumed, 
but the heart-w^cod is rarely or never restored to its 
normal color. Black-heart often results from other 
causes than cold, as from bacteria that gain access to 
the heart-wood through wounds (418). 

Other chemical changes result from cold, as the 
sweetening of potato tubers when chilled, the removal 
of astringency from the wild grape and persimmon, 
and the heighteniilg of the flavor of the parsnip. 

193. Tree Trunks are sometimes Split Open by 
Severe Freezing, the split remaining open until the re- 
turn of mild weather. This most often occurs in hard- 
wooded, deep-rooted deciduous trees, as the oak, and 

. appears to result from the more rapid contraction of 
the outer layers of the wood in a sudden fall of tem- 
perature. The rents are usually overgrown by the next 
annual wood layer (70). 

The splitting down of the main branches of certain 
varities of the apple tree appears to be favored by the 
expansive force of ice in narrow crotches, which retain 
snow and Avater. Varities the branches of which leave 
the trunk at a wide angle are not subject to this trouble. 

194. Bark-Bursting on the trunks of young apple 
trees often occurs when freezing weather overtakes late- 
growing and hence poorly-matured wood. In severe 
cases, the bark splits longitudinally entirely through 
the cambium layer and from the ground to the lower 



126 Principles of Plant Culture. 

branches ; and the bark is loosened from the wood 
nearly or quite around the trunk. Such trees are prac- 
tically ruined, but trees slightly injured by bark burst- 
ing may fully recover. 

Bark-bursting is usually most severe on deep, rich, 
moist soil and in seasons that favor late growth, or in 
which freezing weather occurs unusually early. Late- 
growing varieties are most subject to it. Its occurrence 
is lessened by treatment that favors early maturity of 
the wood (199, 200). 

195. Root-Killing of trees. When a very dry au- 
tumn passes to winter without rain or snow, the surface 
layers of the soil sometimes freeze so severely as to de- 
stroy the roots of trees. Root-killing is usually most 
serious on light soils, and on one-year-old, root-grafted 
(391) nursery trees, especially when grafted with short 
cions (386). With very severe freezing on bare ground, 
root-killing sometimes occurs on soil well supplied with 
water. The destruction of the roots may be complete 
or only partial. In the latter case, the tree, if of a 
vigorous variety, may largely outgrow the trouble, 
though complete recovery is rare. 

Treatment that prevents late growth (199, 200), or 
mulching the ground about trees tends to avert root- 
killing. 

196. Flower-Buds are often Destroyed by Cold 
while other parts of the plant are uninjured. This fre- 
quently occurs in the peach, cherry, apricot, nectarine 
and certain species of the plum in climates of rather 
severe winters, especially after the buds have been 
somewhat excited by unseasonable warm weather. 



During the Dormant Period. 127 

Flower-buds thus destroyed are dark-colored at the 
center. Often only a part of the embryo flowers on a 
tree are destroyed. 

197. Flowers are Especially Sensitive to Cold. Fruit 
crops are usually wholly or in part cut off if a slight 
frost occurs during bloom, and in certain fruits, as the 
apricot and some species of the plum, the blossoms 
sometimes appear to be destroyed by a degree of cold 
that does not descend to the freezing point, possibly 
through interference with pollination or pollen germi- 
nation (150). When the freezing is accompanied with 
snow, however, open flowers may escape without harm, 
probably owing to the slow extraction of the frost 
(189 b). 

198. Low Plants are often Destroyed by Ice, espe- 
cially when the ice layer forms in direct contact with 
the soil about them and remains for a time after the 
return of warm weather. The same effect results some- 
times from a covering of snow, of which the top has 
formed into a crust of ice. Winter grain, strawberry 
plants and lawn grass are often smothered in this way. 
Surface drainage of ground devoted to such crops is 
highly important. 

Section II. Methods of Averting Injury by Cold. 
A — During the Dormant Period. 

a— By Treatment of the Soil. 

199. A Dry Soil Favors Wood Maturity, while an 
abundant water supply retards it. Soil treatment that 
restricts the water supply toward the close of the grow- 



128 Principles of Plant Culture. 

ing period tends, therefore, to hasten wood maturity 
and thus to reduce damage from cold (174). Tillage 
should be early discontinued about trees liable to win- 
ter injury, and in wet seasons, mulching should be re- 
moved. Oats, buckwheat or clover sown in the nursery 
or orchard in late summer promotes wood maturity by 
increasing evaporation from the soil and is further 
useful as a covering to the ground in winter (195). 
Draining heavy or wet soils promotes wood maturity 
by promptly removing surplus water, 
b — By treatment of the plant. 

200. Pinching the Terminal Buds (416 a) a few 
weeks before the time for leaf fall favors wood matur- 
ity by checking growth, as does the removal of the 
younger leaves, in which food preparation is most ac- 
tive. These methods may be employed upon young 
trees — especially nursery trees, which are very liable to 
make late growth. Early gathering of the fruit from 
trees of late varieties also tends to hasten wood maturity. 

201. Protection with Non-Conducting Materials 
prevents damage from cold in many herbaceous and 
shrubby plants in climates where they are not fully 
hardy. By covering such plants with straw or other 
litter, or with soil, we lessen to some extent the in- 
tensity of the cold, but — more important— we prevent 
frequent freezing and thawing (189 d), and in a meas- 
ure, the heaving of the ground, which on heavy or wet 
soil is destructive to the roots of plants. A covering of 
straw, leaves or other litter is preferable for low, her- 
baceous plants, as strawberries. The covering should 
not exceed an inch or two in thickness, otherwise the 



Injury from Cold During Growing Period. 129 

plants may be smothered in warm winter weather. For 
taller plants, as the grape and raspberry, the soil is 
usually the most convenient and satisfactory covering, 
as a litter covering tends to attract mice, that often 
injure woody stems. To assist in bending down the 
stems, a little earth is usually removed at the base on 
the side toward which they are to be bent. Shrubs too 
large for bending down may be inclosed in straw or 
similar material. 

202. A Northerly Exposure is generally Least Try- 
ing to Plants in winter, because it is least subject to 
fluctuations in temperature. The influence of the sun 
is here less perceptible and snow remains longer than 
upon other exposures. The summit of a hill is usually 
less trying than a valley, because the cold air tends to 
seek the lower places, especially in still weather (209). 

203. Wind-Breaks, i. e., plantings of trees intended 
to break the force of prevailing winds, act beneficially 
in lessening damage from cold, in so far as they prevent 
snow from drifting off the soil and mitigate the effects 
of drying winds (189 c). 

B — Methods of Averting Injury from Cold During 
THE Growing Period. 

204. Plants are much more susceptible to injury from 
cold during their growth period than during their dor- 
mant period (170). Comparatively few plants, how- 
ever, are injured by cold at any season until the tem- 
perature falls below the freezing point of water (32° F., 
0° C), or when so-called Jioarfrost occurs. It is this 



130 Principles of Plant Culture. 

extreme that we have chiefly to fear and to guard 
against during the growing period. 

205. The Cause of Hoarfrost. A sponge saturated 
with water cannot be compressed in the least unless 
a portion of the water escapes. If it is but half satu- 
rated, it may be compressed somewhat without any es- 
cape of the liquid, but if the compression passes a cer- 
tain limit, the water will begin to escape. 

The air is like a sponge in being capable of taking up 
a certain amount of water. But the amount of water 
the air can take up depends much upon its temperature, 
its capacity for water increasing as the temperature 
rises, and decreasing as it falls. 

Suppose a given amount of air at a temperature of 
50° F. has taken up all the water it can hold at that 
temperature. It is clear from what has just been said, 
that if the temperature of this air is reduced, some of 
its water will be set free or precipitated. If the air 
were only half saturated at 50° F., its temperature 
could be reduced considerably before any of its water 
would be precipitated; but when a certain degree of 
cooling is reached, the air will no longer be able to hold 
all of its water, and a part will be precipitated. The 
cooling of the air corresponds to the compression of the 
sponge. The atmosphere always contains more or less 
water in the form of watery vapor, and the tempera- 
ture at which any portion of the atmosphere on cooling 
begins to precipitate a part of its water, is called the 
dew point. The temperature of the dew point depends, 
therefore, upon the amount of water the air contains. 



Injury from Cold During Growing Period. 131 

When the dew point is above the freezing point of water 
(32° F., 0° C), the precipitation is in the form of dew 
or rain ; but when it is below the freezing point of 
water, the precipitation is in the form of hoarfrost or 
snow. One more principle needs to be explained, and 
we are ready to understand. 

206. How Frost may be Foretold. We know that 
sprinkling the floor of a room cools the air, even though 
the water used is no cooler than the air of the room. 
This is because the air in taking up watery vapor ab- 
sorbs heat, but this heat is set free again when the 
watery vapor is precipitated. A steam radiator gives 
out heat because the steam within it is condensing into 
water. It follows that when the dew point of the at- 
mosphere is reached, a very considerable amount of 
latent heat is given off, which checks the fall of tem- 
perature. The temperature of still air, therefore, rarely 
falls much helow the dew point, and since the latter at 
any given temperature depends upon the amount 
of the moisture in the air, if we have an instrument 
capable of indicating both the temperature and the 
moisture of the air, we may compute the lowest tem- 
perature to which the atmosphere will be likely to de- 
scend during any given night, and thus we may fore- 
tell frost with some degree of certainty. 

207. The Sling Psychrometer (psy-chrom'-e-ter) 
enables us to determine both the temperature and the 
moisture of the air. This instrument consists of two ac- 
curately-graduated thermometers attached to a board 
or case (Fig. 59). The bulb of one thermometer is 



132 



Principles of Plant Culture. 



M. 









C^^ ^~^^i 




TRY 




1^0- ■ 




- 130 




130- ■ 
120- ■ 




- -IOC 

- -lo 




90- 




- ■ 80 




80- 




- . 70 




70- • 




- to 




60- ■ 





- 50 




50- ■ 




- 40 




,0- ■ 




- 30 




30- h 




- 20 




10- ■ 












M. 





inclosed in thin muslin, which is wet just before using 
the instrument by dipping the bulb in rain water, or 
is connected with a small vessel containg rain water, 
as shown. By means of a string attached to the board 
or case at the end opposite the bulbs, 
the instrument is whirled about in the 
air a few times, after which the ther- 
mometers are quickly read and the 
difference in the readings noted. 
When the air is comparatively dry, 
evaporation from the muslin proceeds 
rapidly, and on account of the heat 
absorbed, the wet bulb indicates a 
lower temperature than the dry one. 
When the air is damp, evaporation is 
slower, and the difference between the 
readings of the two thermometers is 
less. In saturated air, evaporation 
ceases and the two thermometers read 
alike. By means of the following table, the dew point 
for any ordinary out-door temperature and atmospheric 
humidity during the growing season may be readily 
determined. 

2o8. To Compute the Dew Point. Find the wet- 
hulh depression by subtracting the wet-bulb reading 
from that of the dry bulb ; locate this in the top line of 
the table, and find the dry-bulb reading in the left hand 
vertical column. Opposite the dry bulb reading, in 
the column headed with the number indicating the wet- 
bulb depression, is the dew point sought. 



Fig. 60. Sling psy- 
chrometer, used 
to foretell frost. 



Injury from Cold During Growing Period. 133 

Example: Dry-bulb reading 47° 

Wet-bulb reading 40° 

Wet-bulb depression 7° 

Table for Computing the Deiv Point in Degrees 
Fahrenheit. 

Dry 
Bulb. Wet-Bulb Depression. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


10 


II 


12 


13 


^6 


32 


30 


27 


24 


21 


18 


13 


+8 
9 


-1 


-19 


-3-? 






S7 


34 


32 


29 


25 


91 


19 


15 


+3 

+6 

8 


— 7 


-93 






S8 


35 


38 


30 


96 


93 


19 


17 


11 


— 3 


-16 






39 


36 


34 


31 


28 


24 


20 


16 


14 





-11 


-31 




40 


37 


35 


32 


29 


26 


22 


18 


12 


10 


+ 3 


- 6 


-22 




41 


39 


36 


33 


30 


27 


23 


19 


14 


8 


+ 6 


- 2 


-15 




42 


40 


37 


34 


31 


28 


25 


21 


16 


10 


+ 3 


- 2 


- 9 


-29 


43 


41 


38 


35 


33 


30 


26 


22 


18 


13 


+ 6 


- 3 


— 5 


-20 


44 


42 


39 


37 


34 


31 


27 


24 


20 


15 


9 


- 1 


-12 


-18 


45 


43 


40 


38 


35 


32 


29 


25 


21 


17 


11 


+ 4 


- 7 


-27 


46 


44 


41 


39 


36 


33 


30 


27 


23 


19 


14 


+ 7 


_ 2 


-18 


47 


45 


43 


40 


37 


35 


32 


28 


25 


21 


16 


10 


+ 2 


-11 


48 


46 


44 


41 


39 


36 


33 


30 


26 


22 


18 


12 


+ 5 


- 6 


49 


47 


45 


42 


40 


37 


34 


31 


28 


24 


20 


15 


+ 8 


- 1 


50 


48 


46 


43 


41 


38 


36 


33 


29 


26 


22 


17 


11 


+ 3 


5 1 


49 


47 


45 


42 


40 


37 


34 


31 


27 


23 


19 


13 


6 


52 


50 


48 


46 


43 


41 


38 


35 


32 


29 


25 


21 


16 


9 


53 


51 


49 


47 


44 


42 


40 


37 


34 


30 


27 


23 


18 


12 


54 


52 


50 


48 


46 


43 


41 


38 


35 


32 


28 


24 


20 


15 


55 


53 


51 


49 


47 


45 


42 


39 


36 


33 


30 


26 


22 


17 


56 


54 


52 


50 


48 


46 


43 


41 


38 


35 


32 


28 


24 


19 


57 


55 


53 


51 


49 


47 


45 


42 


39 


36 


33 


30 


26 


22 


58 


56 


54 


52 


50 


48 


46 


43 


41 


38 


35 


31 


28 


24 


59 


57 


55 


53 


51 


49 


47 


45 


42 


39 


36 


33 


29 


26 


60 


58 


56 


54 


52 


50 


48 


46 


43 


41 


38 


35 


31 


28 


61 


59 


57 


56 


54 


52 


49 


47 


45 


42 


39 


36 


33 


29 


62 


60 


58 


57 


55 


53 


51 


48 


46 


43 


41 


38 


35 


31 



Opposite 47°, in the left hand column, and under 7 
in the top line, we find 28°— the dew point. If these 
readings are obtained toward sunset on a clear, still 
evening, we should expect frost, because the dew point 



334 Principles of Plant Culture. 

is 4° below the freezing point of water. A slight 
wind, a hazy atmosphere, or a few fleecy clouds would 
render frost doubtful. With a dry-bulb reading of 45^ 
and a dew point of 25°, a killing frost might be ex- 
pected. 

209. Cold Air Drainage. Warm air, being lighter 
than cold air, tends to rise, while the colder air tends to 
fall. In a still atmosphere, therefore, the cold air accu- 
mulates in the lowest places. This explains the familiar 
fact that hollows and valleys are colder in still weather 
than ridges and mountains. In a falling temperature 
and in the absence of wind, gentle currents of the colder 
air tend to follow the water courses, which explains in 
part why frost so often "goes in streaks." 

210. Wind Tends to Avert Frost because it prevents 
the settling of the colder air and thus keeps the tem- 
perature of the lower strata of the atmosphere nearly 
uniform. 

211. Clouds, Haze and Smoke Tend to Avert Frost 
because they act to some extent like a blanket in pre- 
venting the radiation of heat from the earth, and thus 
check the fall in temperature (216). 

212. The Proximity of a Body of Water Tends 
to Avert Frost because the water cools slower than the 
air and thus checks the fall in temperature of the at- 
mosphere in the vicinity; also because it keeps the 
neighboring atmosphere moist, thereby raising the tem- 
perature of its dew point (205). The proximity of 
buildings and trees tends to avert frost, probably be- 
cause these objects give up their heat gradually and 
thus temper the surrounding atmosphere. 



Injury from Cold During Growing Period. 135 

213. The Localities Most Subject to Untimely 
Frosts are narrow and deep valleys inclosed on all 
sides, and inclined valleys that serve as channels 
through which cold air flows to lower levels. Partially- 
cleared districts usually suffer more from frosts than 
those fully cleared, because the remaining forests ob- 
struct air drainage. 

Marsh areas are subject to frost, because, in addition 
to their low situation as compared with the surrounding 
land, their luxuriant vegetation tends to cool the at- 
mosphere in the vicinity by exposing a large radiating 
surface and promoting abundant evaporation. 

Valleys surrounding elevated lakes that have an out- 
let through which the colder air may flow to lower re- 
gions are particularly free from damaging frosts. The 
valley of Keuka Lake, in west-central New York, so 
famous for its vineyards, is of this class. 

214. Thermal Belts. In some elevated districts of 
mountainous regions, localities of greater or less extent 
are found in which damaging frosts are almost unknown. 
These have been called thermal 'belts, and their freedom 
from frost is explained by the merging of the warm air, 
that rises somewhat rarified by heat from the lower val- 
leys, with the atmosphere of the more elevated region 
that is rarified to an equal extent by the high altitude. 
Thus the warm air ceases to rise, but lends its heat to 
temper the climate of the adjacent mountains. 

215. Liability to Damaging Frost Depends Com- 
paratively Little upon Latitude. Within the tropics 
are areas where frcst is unknown because the temper- 



136 Principles of Plant Culture. 

ature never falls to the freezing point. But in local- 
ities subject to frost, the liability of damage to vegeta- 
tion from this cause is goverened more by cold air 
drainage (209) and proximity to water than by latitude. 
It is as important to select locations for peach growing 
with reference to spring frosts in the Carolinas as in 
the peach belt of Michigan, and favorable locations for 
the apple in "Wisconsin sometimes escape damage from 
spring frosts in seasons when the apple crop is cut off 
by frost from extensive regions of the southern states. 

216. Methods of Preventing Injury by Frost. Any 
non-conducting material lying between the earth and 
space, whether spread directly upon the earth or at a 
considerable height above it, acts as a blanket to inter- 
cept the radiating heat, and thus prevents in a measure 
the cooling of objects beneath it. For this reason, 
straw, muslin or other non-conducting material spread 
over plants, usually protects them from frost. 

While it is easy to protect a few plants from frost 
by covering them directly, it is much more difficult to 
protect large plantations in this manner. Considerable 
plantings of the strawberry have been successfully pro- 
tected from frost by covering the rows in the evening 
with straw or marsh hay, and where these materials 
are convenient, the work may often be cheaply and 
quickly performed. 

Attempts to prevent frost on a large scale by the 
heat of fires or by burning material that produces much 
smoke or vapor, have not been sufficiently successful to 
commend these methods for general application. 



Plants as Affected hy Excessive Water. 137 

Section III. The Plant as Affected by Unfavor- 
able Water Supply. 

A — By Excessive Water. 

217. Excessive Water in the Soil Destroys the 
Roots of plants. We saw that oxyg-en is necessary to 
the life of roots (89). When the soil cavaties are 
filled with water, the roots are soon deprived of oxygen, 
because the little oxygen contained in the water is soon 
exhausted (93). Smothering and decay of the roots 
follow. Seeds planted under such conditions usually 
fail. The soil water that is most useful to land plants 
is that which remains attached to the earthy particles 
after percolation has nearly ceased (capillary water). 
Such water is well aerated because it is interspersed 
with cavities that are filled with air (91). 

In the open ground, the remedy for excessive soil 

water may usually be found in underground drainage. 

But the same trouble often occurs in potted plants, as 

the result of too compact soil or too copious watering. 

The expert recognizes this condition by a sour odor of 

the soil, by lifting the pot, or by tapping the pot with 

his knuckle. If the soil is soggy, the weight will betray 

the fact, or the sound given out by the pot will be that 

of a compact mass instead of a more or less hollow 

body, as is the case with a pot of well-aerated soil. To 

remedy the evil, repot the plant in fresh soil of a 

proper condition of moisture, providing abundant 

drainage at the bottom of the pot (412). 
10 



138 Principles of Plant Culture. 

218. Injudicious Watering is perhaps the most 
common cause of faihire in growing potted plants. 
The amateur to often assumes that the chief need of 
the plants is frequent watering, and so gives water in 
spoonful doses as the surface soil of the pot appears 
dry, without observing the state of the soil beneath. 
The roots of the plants in the meantime may be smother- 
ing in water-logged soil or starving from drought. If, 
owing to inexperience, the condition of the soil can- 
not be determined by the means above noted, the soil 
may be tipped out upon the hand without materially 
disturbing the roots of the plant, by reversing the pot 
and gently striking its rim on the edge of the bench or 
table. The real condition can then be readily de- 
termined. 

219. Copious Waterings at Considerable Intervals 
are Preferable to frequent slight waterings. It should 
never be forgotten that air is as essential as water to 
the well-being of roots (89), and that the soil, however 
porous, requires occasional ventilation (93). A con- 
siderable quantity of water poured upon the surface 
soil of a potted plant, in passing downward not only 
thoroughly moistens the soil particles, but acts like a 
piston, forcing the vitiated air of the soil cavities ahead 
of it and out through the drainage hole at the botom of 
the pot, while fresh air enters from above as the sur- 
plus water passes out beneath. Manure water should 
not often be used, as there is danger in giving the 
plant too much food. 

220. Rapidly-Growing Plants Require More Water 
and are less liable to suffer from over-watering than 



Plants as Affected hy Excessive Water. 139 

slower-growing ones. During the rest period (172), 
plants should be given very little water. 

221. Some Species Require More Water than 
Others. The native habitat of the plant is a partial 
guide to the amount of water needed. Plants native 
to arid regions, as the cacti and those from treeless, 
rocky locations, require little water and are readily 
destroyed by over watering. ''Plants with narrow 
and tough leaves, especially when the leaf -blade is 
vertically placed, do not, as a rule, like much water; 
plants with broad, leathery leaves prefer a damp 
atmosphere to great moisture at the roots. Succulent 
plants with hard epidermal cells (leafless Euphorbias, 
succulent Composites, Aloes and Agaves), and thin- 
leaved plants with a strong wooly covering of hairs are 
further examples of plants which require very little 
water. ' '* 

222. Excessive Watering sometimes Produces a 
Dropsical Condition (oedema) in the leaves of plants 
under glass. This is most likely to occur in winter, 
when sunlight is deficient, especially if the soil is kept 
nearly or quite as warm as the air. Water accumulates 
in the cells, abnormally distending their walls— some- 
times even to bursting. An unnatural curling of the 
leaves, with yellow spots and small wart-like excres- 
cences on their surfaces, are some of the symptoms of 
this trouble. Less water, increased light and reduced 
bottom heat (362 a) furnish the remedy. 

Frencliing, a disease that often attacks growing to- 
bacco on excessively-wet clay soils, may be caused by 

* Sorauer, Physiology of Plants, p. 207. 



140 Principles of Plant Culture. 

undue absorption of water by the roots. The leaves 
of affected plants grow narrow, and are thick, fleshy 
and wrinkled. If the plants are pulled sufficiently to 
break the tap-root, before the disease has progressed too 
far, they often recover. 

223. Water-Sprouts (sap-sprouts, gormands) on 
fruit trees are sometimes due to an excess of water in 
the soil. These thick, rapidly-growing shoots, with re- 
mote leaves and poorly-developed buds, growing from 
the main branches of unthrifty fruit trees, are most 
common on undrained, heavy soils. They rarely pro- 
duce nuich fruit, but tend to rob the bearing branches 
of light and nourishment. They usually continue to 
grow late, and in severe winters are often injured by 
cold. Water-sprouts may also result from over-prun- 
ing and from injury of the tree by cold, but in the ab- 
sence of these conditions they suggest the need of 
drainage. 

224. Fruits and Vegetables often Crack from Ex- 
cessive Moisture, either through too much absorption 
by the roots or by direct absorption through the skin. 
Cracking is most frequent after heavy rains following 
drought. Apples, tomatoes, melons, carrots, kohl-rabi, 
cabbage and potato tubers, are subject to it. On wet 
soils, drainage may largely remedy the evil. The se- 
lection of varieties least subject to cracking is also 
helpful, especially in melons and tomatoes which often 
crack in comparatively dry weather. In these cases, 
the cracking is probably due to an unequal maturing 
of the fruit which causes certain parts to grow faster 
than others. The bursting of cabbage heads is due to 



Plants as Affected hy Excessive Water. 141 

the excessive absorption of water by the rcots. To pre- 
vent it, Ave start the plants by pulling- on the stem suffi- 
ciently to break a part of the roots. 

225. Knobby Potatoes are caused by a wet period 
following a drought during the ripening season. Parts 
of the plant that are still alive, stimulated by abundant 
water, resume growth. But since cell division is possi- 
ble only in the parts containing protoplasm, the ma- 
ture cells of the tuber can no longer divide, hence 
growth is limited to the younger parts, i. e., the vicinity 
of the buds (eyes), and these therefore grow out into 
unshapely protuberances. The knob consumes a part 
of the starch previously stored in the tuber from which 
it grows, hence knobby potatoes are poorer in food 
value than smooth ones of the same lot. 

Certain varieties of potato are more disposed to 
knobbiness than others. In varieties normally free from 
it, the planting of knobby seed tubers probably does not 
tend to increase the inclination to knobbiness. 

226. Excessive Moisture in the Air is Injurious to 
plants, since it tends to hinder normal transpiration 
(74) and favors the growth of certain fungous para- 
sites (321). In the greenhouse, we control the atmos- 
pheric moisture by ventilation and care in the use of 
water. Out of doors, we guard against excessive moist- 
ure in the air by giving plants sufficient room to favor 
the circulation of air between them. The latter precau- 
tion is important in orchard planting, since several 
fungi that prey upon fruit trees, as the apple scab (328) 
and pear blight (323), flourish in a damp atmosphere. 



142 Principles of Plant Culture. 

B — The Pl.ant as Affected by Insufficient Water. 

227. Insufficient Moisture in the Air Causes Ex- 
cessive Transpiration (74), which reduces the tension 
of the cell-walls and thus retards growth (62). It also 
tends to clog the leaves with useless mineral matters, 
causing their premature death (125), and favors the 
development of certain fungous parasites. The effects 
of insufficient moisture in the air are often very notice- 
able upon plants kept in living-rooms in winter. Such 
plants, especially when few in number, rarely make sat- 
isfactory growth and the lower leaves continually per- 
ish. Moistening the air by evaporating water in the 
room, or setting the pots containing the plants upon a 
table covered with moist sand usually remedies the 
trouble. 

Insufficient moisture in the open air rarely occurs 
unless there is also a dearth of water in the soil. 

228. Insufficient Moisture in the Soil Retards 
Growth both by reducing the tension of the cell-walls 
(62), and by lessening the supply of food from the soil. 
The tendency of drought is, therefore, to starve the 
plant. 

Plants that have been subject to insufficient water 
from the beginning usually suffer less from drought 
than those previously well watered, because their root 
system has become more extensively developed (111). 

229. Drought tends to Hasten Maturity, especially 
in annual plants, since it favors flowering (134). Let- 
tuce, spinach, rhubarb, etc., "run to seed" earlier if 
insufficiently supplied with water. Potatoes usually 



Plants as Affected hy Insufficient Water. 143 

ripen earlier in dry seasons than in wet ones. If the 
drought is sufficiently severe or sufficiently prolonged, 
diminution or failure of seedage results. 

230. Toughness of Plant Tissues Results from 
Drought. The crispness and tenderness that give qual- 
ity to salad vegetables, as celery, lettuce, radish, etc., 
due to a distended condition of their cell-walls, is 
largely wanting when the water supply during growth 
has been insufficient. 

Insufficient water during growth injures the quality 
of tobacco. Leaves thus affected have a peculiar spot- 
ted appearance when cured, and do not "sweat" 
properly. 

231. Crumbling of the Surface Soil (cultivation) 
tends to Prevent Drought, since it greatly lessens the 
points of contact in the soil particles, and thus inter- 
feres with the rise of the soil water by capillary attrac- 
tion to the surface where evaporation chiefly occurs. 
An air-dry surface layer of crumbled soil also tends to 
prevent evaporation by keeping the soil cooler beneath. 
A puddled crust on the surface of the soil, as is formed 
by rain ^n soils containing clay, tends, on the other 
hand, to restore capillary action and thus to promote 
evaporation. Some gardeners cultivate their hoed crops 
as soon as possible after rains for the main purpose of 
breaking this crust and thus stopping the capillary 
action. 

Cultivation is also beneficial by aerating the soil (93). 
The roots of plants should never be forgotten nor 
ignored in cultivating crops (109). 



144 Principles of Plant Culture. 

232. Mulching tends to Prevent Drought by inter- 
posing a layer of poor-conducting material between the 
ground and the sun's rays. This keeps the surface soil 
cooler and so checks evaporation. 

The best mulching material is the one that conducts 
both heat and moisture slowest. Straw, marsh hay, 
leaves, manure, shavings, sawdust, spent tan and sand 
are all useful for mulching, but the first four named 
are generally preferable to the others, especially if free 
from weed seeds. 

Growing plants tend to dry the soil because the root- 
hairs continually draw in soil water and force it into 
the leaves (101) where it passes off by transpiration 
(74). Weeds, therefore, rob crops of moisture (336). 

233. Irrigation, i. e., the extensive watering of out- 
door plants, is the final remedy for drought. It is nec- 
essary to plant culture in arid regions, and may be 
profitably employed at certain times in the great ma- 
jority of seasons in many localities where the annual 
rainfall would satisfy the needs of crops, were it more 
uniformly distributed. 

234. Drying beyond a certain limit Kills Plant Tis- 
sues by destroying in part their power for conducting 
water. Care should be used to retain the normal moist- 
ure in buds (394), cuttings (358), and cions (386) and 
in the roots of plants lifted for transplanting. 



Plants as Affected hy Excessive Light. 



145 



Section IV. Plants as Affected by Unfavorable 

Light, 

A — By Excessive Light. 




^-S^-^-'^i^^^- 



235. The Unobstructed Rays of the Sun are often 
Injurious to young" seedlings, to unrooted cuttings and 
to plants recently 
transplanted. It is dif- 
ficult to separate the 
influences of light and 
heat, since the heat is 
usually greatest where 
the sun's rays are 
brightest ; but bright 
light probably stimu- 
lates transpiration (74) . fig 6I Lath screen used for shad- 
^ ^ ^ ing cold-frames and tender plants in 

independent of heat ^he open ground. (Atter Balley.) 

and thus tends to exhaust the plant of water. Various 
devices are used to break the force of the solar rays. 
In out-door culture, screens of lath (Figs. 61, 62), 
cloth or brush (Fig. 63) are often placed over beds con- 
taining cuttings or ten- 
der seedlings, as of 
many con e-b earing 
trees. Cuttings in the 
nursery may be shaded 
■ ^u"^- ■^- ^^^? ^'^?^^'' S^^'i- °^ l^^'t^' by supporting a board 

inch-wide slats, for shading tender ^ ^^ ^ 

plants and for storing pots and ^vpr flip row nn «linvf 

boxes of slow-germinating seeds. ^^^^ ^^^^ ^^"' "^^ ^noiL 

(After Bailey.) ^^^^^^ ^^^^ g_^) ^ ^^ ^^ 

to protect them during the warmer hours of the day. 




146 



Principles of Plant Culture. 



Shingles, flower-pots or large green leaves, as of the 
burdock, are useful for shading plants of the cabbage, 
tomato, etc. 

In culture under glass, the glass is often thinly 
washed with lime or clay to render it partially opaque. 



.dJkj,AAi^A 



.4^,„5:-^UiiJ.^,- 




Fig. 63. Brush screen, for shading tender plants in the open 
ground. (After Bailey.) 

or lath screens are used either above or below the glass. 
On greenhouse benches, sheets of thin paper or light 
cloth screens are useful for shading cuttings, recently- 
planted seedlings and germinating seeds. 

Shading should never be so put on as to prevent a 
free circulation of air about the plants. 




Fig. 64. Board shade for recently-set plants, or for cuttings 
not yet rooted. 

A shade that obstructs only a part of the rays of sun- 
light at a time, as does the lath or brush screen, is 
generally preferable to one that continuously breaks 
the force of all the rays, as does paper or whitewashed 
glass. 

236. Cauliflower Heads should be Sheltered from 
Sunlight to prevent the formation of chlorophyll in 
their cells (59), which darkens their color and gives 



Plants as Affected hy Insufficient Light. 147 

them a strong flavor. The leaves surrounding the 
head may be tied about it or broken over so as to shade 
it from direct sunlight. Burst cabbage heads should 
be cut at once to avoid the formation of chlorophyll 
within them. 

B — Plants as Affected by Insufficient Light. 

237. Insufficient Light is a Frequent Cause of 
Abnormal Development in plants. Some of its effects 
are 

a — Excessive elongation of the cells of the internodes 
(75), causing the plants to "draw up" or grow spin- 
dling. 

b — Deficient formation of chlorophyll (59), giving 
the foliage a pale-green, yellowish or whitish tint, and 
resulting in 

c — Lessened food formation, causing reduced leaf de- 
velopment and deficient vascular bundles (67). 

d — Reduced transpiration tending to watery, weak- 
celled growth. 

e— "Weakening of the color and flavor of some fruits, 
as the apple and strawberry. 

f — Preventing pollination (150). 

g — Reducing fruitfulness. 

Owing to these causes, plants grown in deficient light 
have tall, slender, weak stems, few, small, pale leaves 
and scanty roots and are often unfruitful.* Such plants, 
though of species that normally grow upright, are 
often unable to stand erect without support. Familiar 



* Tomato plants grown in winter on poorly-lig-hted benches are 
often unfruitful even when they grow well and bloom freely. 



148 Prmciples of Plant Culture. 

examples are cabbage and tomato plants that lop over 
when planted ont, because grown in the sccd-bOA to 
transplanting size without "pricking off" (105) ; and 
grain sown too thickly on rich ground, that fails 
(lodges) before maturity. " 

238. Too Close Planting Causes Deficient Light 
and all the resulting evils. Indian corn grown too 
thickly does not ear well and is lacking in nutritive 
qualities; strawberry plants grown too closely do not 
fruit well and the fruit lacks flavor and firmness ; 
nursery trees grown too closely are slender-stemmed, 
deficient in foliage and have poorly developed roots. 
A rule to govern distance in planting has already 
been given (122). 

When a slender and flexible growth is desired, as in 
trees grown for hoop poles, or willows for wicker-work 
and tying, a certain amount of crowding is advisable. 

239. Weeds Cause Deficient Light in low-growing 
crops as strawberries, dwarf beans, potatoes, etc., and 
also tend to rob the plants of food and moisture. They 
are, therefore, decidedly injurious (336). 

240. Plants Under Glass are Especially Liable to 
Suffer from Deficient Light, because the walls and 
sash bars of the structure necessarily intercept a con- 
siderable part of the solar rays. The roofs of glass 
houses should be formed of large lights of glass, with 
the smallest possible sash bars, and the benches should 
be arranged to bring the plants as near to the glass as 
possible. 

Plants having their leaves densely covered with hairs 
generally require a large amount of light. 



Plants as Affected by Insufficient Light. 149 

241. The Electric Light has been found useful as a 
supplement to the scanty sunlight of short, early-winter 
L^j^ days, in forcing certain vegetables 

and flowers. 

242. Insufficient Pruning Pre- 
vents the formation of Fruit-Buds 
in orchard trees by restricting light 
and thus reducing food formation 
(58). Compare Fig. 65, which 
shows a fruit branch of the apple 
tree grown where exposed to abun- 
dant sunlight, with Fig. 66, showing 
one grown in partial shade.* 

243. Blanching of certain vege- 
tables as celery, endive, cardoon and 
sea kale is practiced by gardeners to 
render them more tender and deli- 
cate. It is effected by excluding the 
light from the parts desired for use, 
until the chlorophyll (57) mostly 
disappears, by banking the plants 




Fig. 65. 



Fig. 66. 



Fig.' 65." Fruit branch with earth or inclosing them in paper 

of apple grown in 

abundant light. ^^ i^ drain-tile. Very close planting 

Fig. 66. Another .7 i » 

grown in partial • ,• u.- j u. • 

shade. IS sometimes practiced to promote 

F. fruit-buds; L. 

leaf-buds. (After blanching. 

Kinney.) ^ 



* See Bulletin No. 37, Rhode Island Agricultural Experiment 
Station. 



150 Principles of Plant Culture. 

Section V. Plants xVS Affected by Unfavorable 

Wind. 

A — By Excessive Wind. 

244. Damage to trees and other plants by excessive 
wind is too familiar to need notice, except to suggest 
preventive measures. 

a — The premature blowing off of fruits may be in a 
measure prevented by planting fruit trees where they 
are more or less sheltered from prevailing winds by 
shade trees, buildings, forests or elevations of land. 
Orchards may be in part protected by planting a wind- 
break on the windward side (203). 

b — Shade trees in exposed situations should be 
headed low, and the head should be formed of numerous 
branches. The higher the head, the more it is exposed 
to wind and the greater is the leverage upon the trunk. 
Several small branches are better able to bear the 
tempest than a few larger ones. 

Shade trees for exposed situations should be of species 
not likely to be deformed by wind. Certain trees, as the 
white maple,*' often develop, one-sided if planted where 
exposed to prevailing winds, while others, as the sugar 
maplef and Norway maple| are not thus affected. 

B— Plants as Affected by Insufficiert Wind. 

245. Insufficient Wind Promotes the development 
of certain Fungus Parasites (321) by favoring an ex- 

* Acer dasycarpum. f Acer saccharinum. % Acer platanoides. 



Plants as Affected by Excessive Food. 151 

cessively moist atmosphere. Orchards too closely 
planted or surrounded by wind barriers suffer more 
from fungous attacks than those having freer circula- 
tion of air between the trees. 

246. Insufficient Wind Promotes Damage from 
Frost by permitting cold air to settle in the lower 
places (209). On these accounts, gardens and fruit 
plantations should not be entirely surrounded by wind 
barriers. 

247. Pollination (150) is Dependent upon Wind in 
many plants, as the coniferous trees, oaks, elms, birches 
and sedges; but as the pollen of such plants is very 
light, their fruitfulness is not often much restricted by 
insufficient wind. 

Section VI. Plants as Affected by Unfavorable 

Food Supply. 

We saw that water is the most important constituent 
of plant food (62) and we have already considered the 
plant as affected by water supply (Section III). But 
a proper supply of the other essential food constituents 
is only second in importance to that of water. 

A — Plants as Affected by Excessive Food. 

248. Excessive food is not the extreme that we have 
most to fear, since natural soils are rarely excessively 
fertile, and we can only make them so by costly meth- 
ods. Indeeed, nearly all the constituents of plant food 
may be present in excess of plants' requirements with- 



152 Principles of Plant Culture. 

out working harm. Nitrogen, However, which aside 
from water is the most potent food constituent, must 
be used with some discretion. 

249. Excessive Nitrogen Stimulates Growth at the 

expense of flowers, seed and fruit. In crops grown for 
these parts, therefore, fertilizers rich in nitrogen must 
be used with caution. Apple, pear and quince orch- 
ards liberally manured with such fertilizers produce an 
excessive, over-succulent growth of wood, that is sub- 
ject to blight and winter injury and forms compara- 
tively few fruit buds. Grain under similar conditions 
forms long, weak straw, with poorly-filled heads. 
Grape vines on over manured ground produce excessive 
wood with few and late-ripening bunches. 

There is little danger of over-manuring, however, 
with crops grown for parts other than flowers, fruit or 
seed, so long as decomposed stable manure is used 
(251). But the more concentrated animal manures, as 
those from poultry and the hog, the chemical com- 
pounds of nitrogen, as nitrate of soda and sulfate of 
ammonia (261), and the so-called ''high-grade" com- 
mercial fertilizers must be used with caution, as they 
may destroy the plants if applied in excess. 

B — PijAnts as Affected by Insufficient Food. 

250. It is difficult to separate the effects of a lack of 
food from those of a lack of water, since the food is 
mainly conveyed to the plant in the soil water (62). 
But even with a proper water supply, if one or more 



Plants as Affected by hisiifficient Food. 153 

of the required food materials is lacking (60), a nor- 
mal plant structure cannot be built up. An excess of 
one food siihstance cannot compensate for the lack of 
another, except in a few instances. 

251. Insufficient Food Dwarfs the Plant in all its 
parts. A dwarfing of the size of the plant body may 
occur, however, without a corresponding dwarfing of 
the seed product; hence plants may often bear their 
maximum amount of seed or fruit without attaining 
their maximum dimensions. Plants grown for seed or 
fruit are, therefore, less likely to be restricted in yield 
by insufficient food than these grown for their leaves, 
stems, roots or tubers. The cereals, for example, pro- 
duce well on land not sufficiently fertile to yield equally 
good crops of tobacco, cabbage, celery, lettuce or pota- 
toes. But with a sufficient restriction of food, the seed 
product will suffer diminution or be wholly cut off. 

252. Crop-Growing Tends to Reduce Plant Food in 
the soil in proportion as the fertilizing components of 
the crops are removed from the land and are not re- 
turned to it, directly or in equivalent. Fortunately, 
considerable plant food is constantly being liberated by 
the disintegration and decay of rock or soil materials, 
or is being deposited from the atmosphere in rain or 
snow, so that it is impossible to exhaust the soil of 
plant food, even with the most improvident culture. 
But the cultivator should aim at the largest returns 
from his soil, and these are impossible without restor- 
ing certain materials that continued crop-removal in- 
variably reduces below the limit of profitable yields. 

11 



154 Principles of Plant Culture. 

253. The Food Elements Most Likely to be Defi- 
cient, wlien plants are properly supplied with water, 
are nitrogen, phosphorus and potassium. These are all 
liberated in greater or less quantities, when vegetable 
or animal material (organic matter) decays in the soil; 
hence all such material has more or less value as fertil- 
izers. But we need not wholly depend upon refus? 
organic matter for fertilizers, since the leguminous 
plants add nitrogen to the soil (259), and compounds 
of nitrogen, phosphorus and potassium may often be 
purchased in artificial fertilizers at prices that place 
them within the reach of the cultivator. 

254. Nitrogen is the Most Important Fertilizing 
Element because it is liberated in smallest amount by 
rock decay and is most expensive in the market. Nitro- 
gen is chiefly used by plants in the form of nitrates, 
i. e., in combination with certain other substances as 
soda, potash, lime, magnesia and iron. Ammonia, 
which is a gaseous compound of nitrogen and hydrogen, 
is also used to some extent by plants. Free nitrogen, 
the most abundant constituent of the air, plays no di- 
rect part in plant nutrition (259). 

255. The Sources of Nitrates in the Soil are 

a— Nitrification (nit-ri-fi-ca-tion), by which the nitro- 
gen contained by organic matter and ammonium sulfate 
in the soil is changed to nitric acid through the agency 
of microscopic plants (bacteria). The nitric acid thus 
formed combines with certain substances (bases) in the 
soil, as potash and lime, forming nitrates (254). 

h— Symbiosis (sym-bi-o-sis) on the roots of legumin- 
ous crops, through which atmospheric nitrogen Is 
changed to nitric acid (259, 112). 



Plants as Affected hy Insufficient Food. 155 

G— Deposits from the atmospliere in rain or snow 
(260). 

d — Ammonium salts or nitrates applied to the soil 
(261). 

256. The Conditions Affecting Nitrification are sim- 
ilar to those affecting plant life in general, since nitri- 
fication results from plant life. As it takes place be- 
low the surface of the soil, it is favored by the same 
conditions that favor the root growth of land plants, 
viz., aeration, w^armth and moisture. In general, it is 
active during the growing season, but at a standstill 
during the dormant period. It does not proceed rap- 
idly in spring until the soil has become sufficiently 
warm to promote active root growth. 

Nitrification also releases the other food materials 
contained by organic matter (92). 

257. Soil Aeration Promotes Fertility by favoring 
nitrification. Thus cultivation and drainage (of heavy 
soils) not only directly promote the growth of plants 
by assisting aeration (93), but they actually increase 
plant food. Early plowing in spring promotes nitrifi- 
cation by favoring warming of the soil. Cultivation 
in dry weather further promotes plant nutrition by 
preventing the accumulation of soluble plant food in 
the dry surface soil, where it is deposited above the 
reach of roots through evaporation. 

258. Partially-Decomposed Organic Manures Act 
More Promptly than fresh ones, because nitrification 
has alreadv commenced in these materials. 



156 Principles of Plant Culture. 

259. Leguminous Plants Enrich the Soil with nitric 
acid (255), which is formed from atmospheric nitro- 
gen in the tubercles on their roots through the agency 
of microscopic plants (112). Even when a part of 
these crops is removed from the land, as when clover 
is harvested for hay or peas for their seed, the land is 
richer in nitrogen than before the crop was planted. 
The principal leguminous crops are the clovers, peas, 
beans, lentils, sanfoin, vetches, alfalfa, lupine and cer- 
tain species of Latliyrus. Highly valuable as are these 
crops for the nitrogen they leave in the soil, it should 
be remembered that they do not contribute phosphoric 
acid or potash, and hence must not be wholly depended 
upon for soil fertility (262, 263). 

Leguminous plants are supplied with nitrogen by the 
micro-organisms in their roots (112), and hence do not 
require this element in fertilizers. 

260. Rain and Snow Add Nitrogen to the Soil in 
small quantities, both as nitric acid and ammonia, which 
they have taken from the air, but the amounts thus 
added, while useful to plants, are not under our control. 

261. Nitrogen may be Purchased for fertilizing pur- 
poses ?i^ sodium nitrate {mivdiiQoi soda, Chili-saltpeter), 
ammonium sulfate (sulfate of ammonia), and in organic 
materials. The former is available as plant food when 
dissolved in the soil water. It is best applied imme- 
diately before the planting of a crop or in small quan- 
tities at intervals during growth, since it is in danger 
of being washed out of the soil in drainage water. 
Sodium nitrate is especially useful for garden crops 



Plants as Affected hy Insufficient Food. 157 

started early in the spring, when the soil is too cool 
for active nitrification (255). The surface soil is apt 
to be poor in nitrates in spring, because they are often 
washed down by the autumn and winter rains. 

Ammonium sulfate is changed to nitrates in the soil 
before it is used by plants, and hence is less prompt in 
its action than sodium nitrate. It is more tenaciously 
held by the soil than sodium nitrate and is therefore 
less likely to be lost by washing. 

262. Phosphorus is used by plants in the form of 
soluble phosphoric acid, which exists in the soil in 
combination with lime, iron and alumina, as phosphates 
of these substances. It may be purchased in the form 
of mineral phosphate of lime, ground bone, wood ashes, 
odorless phosphates, etc. The first two are insoluble 
in water unless treated with a strong acid, When they 
are known as acid plwsphate or superphosphate. 
Phosphoric acid is not readily washed out of the soil, 
even in its soluble form. 

263. Potassium is used by plants in the form of pot- 
ash, i. e., potassium combined with oxygen. Potash ex- 
ists in the soil mainly in combination with chlorin 
(chlorid or muriate of potash), with sulfuric acid (sul- 
fate of potash), or with nitric acid (nitrate of potash). 
All these forms of potash are freely soluble in water and 
are immediately available as plant food. Nitrate of 
potash (saltpeter) is a most valuable fertilizing mate- 
rial, since it contains both potash and nitrogen, but 
unfortunately its price is too high to permit of its use 
for this purpose. The muriate, either pure or in crude 
form (kainit), and sulfate may, on the other hand, be 



158 Principles of Plant Culture. 

purchased at reasonable prices. The sulfate is consid- 
ered preferable for tobacco and potatoes as it is thought 
to produce a better quality of product. The muriate 
acts more promptly than the sulfate, however. 

264. Wood Ashes are a Valuable Fertilizer, espe- 
cially when unleached, as they contain both potash and 
phosphoric acid. In leaching, the potash is mostly 
washed out, but the phosphoric acid is largely retained. 
Ashes contain no nitrogen. 

265. Farm and Stable Manures should be the first 
dependence of the cultivator. Aside from these, legu- 
minous crops (259) are undoubtedly the cheapest source 
of nitrogen for the farm, and with unleached wood 
ashes, furnish all the needed fertilizing ingredients for 
grain crops grown in rotation. For garden crops, how- 
ever, if sufficient stable manure can not be obtained, 
more nitrogen may often be profitably used than can 
be furnished by leguminous crops, hence for these, com- 
mercial fertilizers may often be added with advantage. 

266. Crops Suggest Their Own Needs to some ex- 
tent, so long as they are not suffering from drought. 
As a rule, a lack of nitrogen is indicated by pale-green 
foliage or small growth of leaf or stalk. Excess of 
nitrogen is indicated by very large growth of leaf or 
stalk, with imperfect bud-, flower- and fruit develop- 
ment. Lack of phosphoric acid is indicated by scanty 
crops of light or shrunken seeds on plants of normal 
size. Lack of potash is indicated by small crops of in- 
ferior fruit, accompanied by satisfactory growth. 

267. Crop Rotation Economizes Plant Food, be- 
cause some crops use more of a given food constituent 



Plants as Affected hy Parasites. 159 

than others. The alternating of crops having different 
food requirements tends to prevent the exhaustion of 
special food substances. Crop rotation also aids in 
avoiding damage from injurious insects and fungi. 

268. A Growing Crop Tends to Conserve Fertility, 
because it reduces drainage by taking up water from 
the soil, and at the same time, appropriates the avail- 
able plant food, thus preventing loss of the latter from 
leaching. 

269. Manures are, in part, the Raw Material from 
which the cultivator turns out valuable products. They 
should, therefore, be most carefully preserved and ap- 
plied. Leaching of the manure pile by undue expos- 
ure to rain and over-rapid fermentation, by which ni- 
trogen escapes as ammonia or other gaseous nitrogen 
compounds, should be stringently avoided. All refuse 
organic matter should, so far as possible, be made to 
increase the always too-small stock of manure. 

Section VII. Plants as Affected by Parasites. 

The only instance of a beneficial plant parasite (24) 
of special interest to the cultivator, is the micro-organ- 
isms in the roots of leguminous plants, which we have 
already considered (259). Many parasites of harmful 
insects are beneficial, but these are beyond our scope. 
We need, therefore, to treat here only those parasites 
that are directly injurious to economic plants. 

270. The Injurious Parasites of plants are Very 
Numerous and a scientific classification of them is be- 
yond the limits of this work. We shall only endeavor 



160 Principles of Plant Culture. 

to arrange the different parasites into groups based on 
their manner of working injury and the methods by 
which they may be controlled. 

With reference to the character of their injury and 
the preventives used, as well as in their natural char- 
acteristics, plant parasites are readily separable into 
two great classes, viz., animal and vegetable parasites. 
These classes will be considered in their order. 

A — Plants as Affected by Animal Parasites. 

a — By quadrupeds and birds. The four-footed 
animals that injure cultivated crops nearly all belong to 
the class known as rodents, which includes mice, go- 
phers, rabbits, woodchucks, moles, etc. These may 
usually be controlled by trapping, shooting, or poison- 
ing, or by protecting the plants. 

271. Damage from Mice to orchard and nursery 
trees is very common. Mice are usually more trouble- 
some on sod ground covered with snow, especially be- 
neath snow banks, hence all grass should be removed m 
autumn from the immediate vicinty of the trees. It 
is well to ridge the soil a little, directly about the trees, 
so that the mice in burrowing beneath the snow will 
not be likely to come in contact with the stems. Pack- 
ing the snow immediately about the trees is helpful 
when damage is discovered during winter. The stems 
of orchard trees may also be wrapped in heavy paper 
or inclosed in fine wire netting. If tarred paper is used, 
it should be promptly removed in spring, or it may in- 
jure the bark. 



Plants as Affected hy Animal Parasites. 161 

Stored seeds of almost all kinds must be carefully 
guarded against mice. 

272. Gophers are often troublesome by eating 
planted seeds and by burrowing about the roots of 
young orchard trees. They may be poisoned by plac- 
ing corn, soaked in a weak solution of strychnine in 
water, about their holes. 

273. Rabbits are especially troublesome to nursery 
trees, when the ground is covered with snow. The 
most satisfactory protection is to inclose the nursery 
with a fence of poultry netting, which should be banked 
up a little at the bottom to prevent the rabbits from 
passing under. It should be high enough to reach above 
the surface of the deepest snow. 

Orchard trees may be protected against rabbits by 
inclosing the trunks with the devices mentioned under 
sun-scald (185). Smearing the stems with blood has 
also been recommended. 

274. Woodchucks are often troublesome to growing 
crops, but as they are seldom numerous, shooting or 
trapping generally suffices to prevent serious damage. 
Moles are very troublesome in some localities by eating 
the roots of plants. They may be largely controlled by 
the use of mole-traps. Pouring a little carbon bisulfid 
into their holes is also generally effectual. 

275. Birds are often troublesome by eating unhar- 
vested fruits and seeds. Inclosing the trees or plants 
with fish netting, when this is practicable, is perhaps 
the most satisfactory preventive. The netting is not 
expensive, and the same piece may be used several 
seasons. 



162 Principles of Plant Culture. 

b — By insects, worms, slugs and snails. As 

worms, slugs and snails work the same kind of injuries 
as some insects and are controllable by the same meth- 
ods, w^e do not distinguish between them in the follow- 
ing paragraphs. 

276. Many Insects are Beneficial by destroying 
harmful insects or by promoting pollination (150). We 
should not, therefore, wage indiscriminate warfare upon 
all insects. 

277. Methods of Preventing Insect Ravages to 
plants are various, as inclosing the plants, trapping, 
repelling or removing the insects, destroying them by 
means of insecticides, or preventing reproduction by 
destroying the eggs. The important question in the 
case of any injurious insect is by which one of these 
methods it may be most effectually and cheaply con- 
trolled. 

278. Inclosing the Plants is practicable in a few 
cases, as wdth the striped cucumber beetle.* The hills 

in which cucumbers, 
melons, squashes, etc., 
are planted, may be 

FIG 67. Screen-covered frame for covered with a frame 
protecting hills of the melon and 

cucumber. having fine-mcshed wire- 

or cotton netting tacked over the top, which prevents 
the beetles from gaining access to the plants (Fig. 67). 

279. Trapping the Insects is practicable in a few 
cases, as with cutworms, which often conceal themselves 
during the day beneath objects on the ground. They 
will frequently be found in numbers beneath handfuls 

*Diabroiica vittaia. 




Plants as Affected hy Animal Parasites. 163 

of green clover or other herbage placed on the gronnJ 
near the plants which it is desired to protect. By pois- 
oning the herbage (283), some of the cutworms may be 
killed, but many are likely to escape unless destroyed 
by other means. 

280. Repelling Insects by means of offensive odors is 
partially effective in some cases, as with the squash- 
vine borer.* Corncobs or other objects, dipped in coal 
tar and placed among the plants, repel many of the 
Tiioths that produce the borers. 

281. Hand Picking, i, e., removing the insects from 
the plants by hand, is the most satisfactory method for 
destroying certain insects, as the tobacco- or tomato 
worm,t and other large caterpillars, and the rose-beetle. t 
A vessel of water with a little kerosene on the surface, 
in which to throw the insects as they are gathered, is a 
convenient way of destroying them. In some cases, the 
insects can be shaken or knocked from the plant directly 
into the vessel. This method is often employed in de- 
stroying the potato beetle. § Digging out cutworms and 
white grubs** from about corn and strawberry plants, 
and cutting out borers from trees and squash vines are 
often the most effectual methods for destroying these 
insects. 

282. Destroying Insects by Poisons or Caustics is 
the method most generally available. The material 
used is called an insecticide (in-sect'-i-cide), and if sat- 
isfactory, must be destructive to the insects without in- 
juring the plant to which it is applied, or rendering 

* Melitia ceto. f Phlegethontius celeus. J Macrodactylus subspinosus. 
I Doryphora clecemlineata. ** Lachnosterna. 



164 Principles of Plant Culture. 

the plant or its products unfit for food. The insecti- 
cides in most general use are certain compounds of 
arsenic (Paris green, London purple, white arsenic), 
hellebore and pyrethrum powders, tobacco, kerosene 
and various compounds of soda and potash. With the 
exception of kerosene and the soda and potash com- 
pounds, all these may be used either as dry powder or 
with water. 

:2B>Z' The Arsenic Compounds are effectual as insect 
destroyers, even when largely diluted. When applied 
in water, however, they are liable to injure foliage in 
proportion to the amount of soluble arsenic they con- 
tain. When insoluble in water, they require stirring 
to keep them in suspension. 

284. Paris Green (arsenite of copper), when pure, is 
a nearly insoluble compound and may be safely used 
upon the foliage of most plants, diluted at the rate of 
one pound to two hundred gallons of water. For the 
peach and nectarine it should be diluted one-half more. 
Pure Paris green dissolves without sediment in ammo- 
nia water. 

285. Arsenite of Lime, a very cheap arsenic com- 
pound, may be prepared by boiling one pound of pow- 
dered white arsenic and two pounds of fresh lime in 
two gallons of water for twenty minutes, stirring occa- 
sionally. For use dilute to 400 gallons. This costs 
only one-fourth as much as Paris green. 

286. Arsenate of Lead contains less soluble arsenic 
than Paris green and remains longer in suspension. To 
prepare arsenate of lead* "dissolve 24 ounces of ace- 

* Bulletin 151, California Agricultural Experiment Station. 



Plants as Affected hy Animal Parasites. 165 

tate of lead (sugar of lead) in one gallon of water and 
separately 10 ounces of arsenate of soda in three quarts 
of hot water. (Use wooden, earthen ware or glass ves- 
sels.) Pour the separate solutions into 100 gallons of 
water. A white precipitate of lead arsenate ready for 
spraying immediately forms in the tank; its fine, floc- 
culent condition keeps it in suspension for hours, and 
of all arsenic compounds it is the most easily kept sus- 
pended in water." 

Arsenate of lead prepared ready for use is offered 
under different trade names, as "Disparene," etc. 

287. London Purple (arsenite of lime, with certain 
impurities) often contains soluble arsenic and like 
white arsenic, must be used with caution. It may be 
safely applied to many plants at the rate of one pound 
to two hundred gallons of water, if put on immediately 
after its addition to the liquid, but for the peach it 
should receive greater dilution. London purple is con- 
siderably cheaper than Paris green. 

The addition of fresh milk of lime to water, to which 
white arsenic or London purple has been added, largely 
prevents their tendency to injure foliage. 

Both Paris green and London purple, when perfectly 
mixed with 150 parts, by weight, of land plaster, or an 
equal bulk of any other cheap, harmless powder, are 
satisfactory for destroying the potato beetle and many 
other leaf -eating insects (307). 

288. Compounds of Arsenic are Deadly Poisons and 
should always be handled with the greatest care. 



166 Principles of Plant Culture. 

289. Hellebore (heP-le-bore) Powder, i. e., the 
ground root of white hellebore,* is a far less virulent 
poison than the arsenic compounds. It is therefore 
useful in destroying a class of insects against which a 
deadly poison cannot wisely be used, as the imported 
currant worm,t and the cabbage caterpillar 4 

Hellebore powder when used dry, may be diluted 
with once or twice its bulk of flour, which causes it to 
adhere better to the foliage than if used alone. When 
applied with water, a heaping teaspoonful or more may 
be added to three gallons. The dry powder is very 
light and should only be used in a still atmosphere. 

A decoction made by boiling the root of white helle- 
bore in water is said to possess insecticide properties 
similar to those of the powder. 

290. Pyrethrum (py-re'-thrum) Powder, (Persian 
insect powder, Dalmatian insect powder, Buhach) is 
the pulverized flowers of certain species of Pyrethrum. § 

Pyrethrum powder is not poisonous to the higher ani- 
mals, but the oil that pervades it is destructive to many 
insects. As the oil is extremely volatile, pyrethrum is 
better adapted for use under glass or with plants other- 
wise inclosed. It is not injurious to foliage or flowers. 
Fresh and pure pyrethrum powder may be diluted half 
or more in bulk with any other light, cheap, harmless 
powder, but the mixture should stand a day or two be- 
fore use, to enable the diluent to absorb the oil. The 

* Verairuni album. \ Nematus rtbeiiii. I Pier is rapce 

I "Persian insect powder" is made from the flowers of Pyre- 
thrum roseum and P. carneum; "Dalmatian insect powder" and 
"Buhach" are made from those of P. cineraioefohum. "Buhach" 
is the trade name of a pure product prepared in California. 



Plants as Affected hy Animal Parasites. 167 

powder may be used with water at the rate of half a 
pound to three gallons. 

The pyrethrum plant is comparatively hardy and has 
been successfully grown in northern United States. It 
is said that a decoction of the unopened flowers posses- 
ses the insecticide properties of the commercial product. 

291. Hellebore and Pyrethrum Powders should be 
Kept in Close Vessels, since their poisonous properties 
are volatile. In purchasing, only fresh samples should 
be accepted. If fresh and pure, these powders produce 
a tingling sensation when applied to the nostrils. 

292. Tobacco Smoke is much used for destroying 
"lice" or ''green fly" (aphidse) on plants under glass. 
For this purpose, the partially-dry stems or leaves are 
burned upon pans or bricks, or in small sheet-iron 
stoves. Many delicate flowers are, however, injured by 
tobacco smoke. 

Stems or leaves of tobacco, strewn abundantly be- 
neath greenhouse benches, tend to prevent the mulit- 
plication of aphidse. 

Several semifluid extracts of tobacco are sold which 
may be evaporated in the greenhouse over an oil stove, 
or preferably by steam under pressure. Some of these 
are very efficient for destroying insects and do not in- 
jure flowers. 

293. A Strong Decoction of Tobacco is often used 
for destroying aphidog on plants in rooms where tobacco 
smoke would be objectionable. The plants are im- 
mersed in, or washed with the decoction. The same is 
often effectually used on young plants of cabbage, cau- 



168 Principles of Plant Culture. 

liflower and turnip, to prevent their destruction by the 
flea beetle.* 

294. Kerosene is a very useful insecticide for a class 
of insects not readily destroyed by other means (316). 
It has generally been used as an emulsion made with 
soap and water, for which the following formulas are 
good. 

a— Dissolve one quart of soft soap, or one-fourth 
pound of good hard soap, in two quarts of boiling 
water; remove from the fire, and pour into a can con- 
taining one pint of kerosene. Agitate violently in the 
can for three minutes. For use, dilute with an equal 
quantity of water; or 

b — Dissolve one-half pound of hard soap in one gal- 
lon of boiling soft water; add at once two gallons of 
kerosene, and churn or otherwise violently agitate for 
five or ten minutes. For use, dilute with 15 parts of 
soft water. 

Kerosene may also be applied in intimate mixture 
with water, secured by pumping both liquids at once 
through a good spraying nozzle (Fig. 70). About ten 
per cent, of kercsene should be used for most plants. 

295. Caustic Potash in solution is useful for destroy- 
ing certain scale insects, as the oyster-shell bark-louse,"|* 
for which solutions of one-fourth pound to the gallon 
of water may be applied during winter. 

296. Resin (or rosin) Washes are valued for destroy- 
ing various scale insects in southern and western United 
States. They are adapted with modifications to both 
dormant and growing trees. The resin is sometimes 



* Phyllotreta vitfaia. \ Mytilaspis pomorwm. 



Plants as Affected hy Animal Parasites. 169 

saponified with caustic soda and simply diluted with 
water; fish oil or petroleum may also be added. The 
following and other formulas are in use: 

a— Dissolve one pound of caustic soda in one gallon 
of water in a covered iron kettle. Pour out half of the 
solution, and to the remainder add 8 pounds of resin 
and boil until dissolved. Then pour in very slowly the 
rest of the caustic soda solution and boil the whole, 
stirring it constantly, until it will unite with water, 
forming a liquid resembling milk. Dikite to 22 gallons 
for use. This mixture may be applied during the grow- 
ing season; or 

b — Place 30 pounds of resin, 9 pounds of 70 per cent 
caustic soda and 4% pints of fish oil, in a closed iron 
kettel and cover with five or six inches of water. Boil 
until the liquid has a dark-brown color, after which 
slowly add water until the whole makes 100 gallons ; or 
dilute a part of the liquid at this rate, keeping the re- 
mainder as a stock solution. This is for use in the dor- 
mant season. For the growing season, similar, but more 
dilute solutions are used. 

297. Hydrocyanic Gas. Another method of destroy- 
ing scale insects is to treat the tree, previously inclosed 
in an oil-cloth tent, with hydrocyanic gas. One ounce 
of cyanid of potassium and one measured ounce of sul- 
furic acid are placed in an earthen or leaden jar con- 
taining three fluid ounces of water. The jar is covered 
with burlaps to prevent the rapid escape of the gas. 
The tent is left over the tree fifteen minutes to one 
hour. It is advisable to apply this treatment during 

the dormant season and in a cool period. Nursery 
12 



170 Prhiciples of Plant Culture. 

stock is now required by law in some localities to be 
treated with hydrocyanic g^as before shipment, to pre- 
vent the dissemination of dangerous scale insects. 

298. Fir-Tree Oil is considerably used in greenhouses 
and conservatories for destroying scale insects and the 
mealy bug.* It is mixed with warm soft water at the 
rate of a tablespoonful of oil to a pint, and applied 
with a .syringe; or the plants are dipped into the 
mixture. 

299. Hot Water may also be used for destroying the 
above named insects (298) and plant lice (aphidae). 
Infested pot-plants are inverted and immersed five or 
six seconds in a vessel containing water at 120° F. 
This treatment must be used with caution. 

Forcible syringing of plants with water is also an 
excellent method of ridding greenhouse plants from 
insects. 

300. Insect Attacks Sometimes Become Formid- 
able from the vast number of the individuals. The 
chinch-bug,t the army-worm| and various species of 
locusts or grass-hoppers sometimes devastate large 
tracts of country. For the destruction of these insects, 
special means must be employed. 

301. The Chinch-Bug may be controlled in a meas- 
ure, by burning over all grass land early in spring, in 
seasons when attacks are expected. The bugs may be 
kept out of corn fields by plowing a furrow away from 
the corn, on the side from which the attack is looked 
for, and strewing stalks of fresh corn in this. As the 
insects congregate on the corn in the furrow, they 

* Dactylopius. f Blissus leucopterus. % Leucania unipuncta. 



Plants as Affected hy Animal Parasites. 171 



should be destroyed with kerosene (294). Persistent 
and thorough work is essential to success. 

302. The Army- Worm may often be prevented from 
migration by plowing a deep furrow, as above directed, 
and making the side toward the endangered crop 'verti- 
cal, with a spade or shovel. The insects will congregate 
in the furrow where they may be destroyed by drag- 
ging a log over them. 

303. Grasshoppers and Locusts may be destroyed, 
before they have attained their wings, by drawing over 
the infested ground a "hopper-doser," which consists 
of a shallow, sheet-iron pan, with a vertical, cloth-cov- 
ered back. The pan contains a little kerosene, and the 
cloth back is kept saturated with the same liquid. The 
insects jump into the pan or against the cloth back, 

thus becoming wet with the kerosene, 
and soon perish. Grasshoppers may 
also be poisoned by dis- 
tributing bran mixed into 
B a mash with water con- 
taining arsenic in solu- 




tion. Plowing grass land 
containing the eggs of 
grasshoppers tends to 
prevent an attack. 

304. Apparatus for 
Applying Insecticides. 
Poii'ders are readily ap- 
plied to low-growing 
plants, as the potato, cabbage, etc., by means of a sift- 
ing box consisting of a pail with a perforated bottom, 



Fig. 68. Sifting box for appply 
ing powders. 



172 



Principles of Plant Culture. 



a rigid handle and a tight-fitting cover (Fig. 68). For 
small plants, as young potato tops, the tin disc A which 
has a circular hole in the center, is laid inside on the 
bottom of the box, and held in place by small lugs 
soldered to the wall as shown. When it is desired to 
spread the powder more, the disc B is used. 

For taller plants, a powder bellows is desirable. 

Liquids are best distributed with a force pump, fit- 
ted with a hose of a length suitable to the height of the 
tree or plant, and with an atomiz- 
ing nozzle (Figs. 69, 70, 71). For 





Fig. 69. 



Fig. 70. 



Fig. 69. A convenient and serviceable spray pump, using a 
common pail for a reservoir. 

Fig. 70. A similar pump with attachment by which kerosene 
and water may be sprayed together (294). Both are made by 
the Deming Co., Salem, Ohio. 



tall trees, the hose nozzle may be elevated by attaching 
it to the end of a light pole. In orchard spraying, the 
pump is often used on a w^agon, and the man holding 
the hose sometimes stands on a high platform. A spray 
pump used on a large reservoir, needs an agitator to 



Plants as Affected hy Animal Parasites. 173 



prevent the heavier part of the spraying mixture from 
settling. 

Excellent bellows and force pumps, designed ex- 
«l"fi^ pressly for applying insecticides, are now 
■ manufactured. 

305. The Use of Insecticides. In treat- 
ing any given insect, the most important 
question to decide, is the manner in which 
it appropriates its food, as upon this will 
depend the preventive measures to be 
used. 

306. Injurious Insects are refer- 
able to Two Classes, viz., 
eating insects, i. e., those 
feeding directly upon the 
plant tissues, as the potato 
beetle, the apple-tree borers,* 
the plum curculio;t and the. 
^,-a sucking insects, i. 

e., those feeding 
only upon the 
juices of the plant, 
as plant lice, the 
squash-bug, t and 
the oyst^er-shell 
bark-louse. § 

307. The Eating 
Insects may be 
subdivided into leaf-eaters, these that devour the foli- 




FiG. 71. steam spraying outfit, manu- 
facT ured by Itlie Shipman Engine Co. 
Rochester, N. Y. 



* The round-headed apple-tree borer. Saperda Candida; the flat- 
headed apple-tree horer, Chrysobothr in femorata. 

\ Conotrachelus nenuphar. X Anasa iristis. I31ytilaspis pomorum 



174 



Principles of Plant Culture. 



age; root-eaters, those that devour the roots; and hur- 
rowers, those that harbor within some part of the plant 
by eating a passage for their bodies. 

308. The Leaf-Eaters include numerous species. 
They are readily recognized by the fact that the leaves, 
on which they feed, disappear more or less rapidly. 
They may generally be destroyed by applying a poison 
to the foliage, for which purpose the arsenical com- 
pounds are well adapted (283). In cases where the 
use of a deadly poison is unsafe, hellebore (289) or 
pyrethrum (290) may be substituted. 

309. The Root-Eaters include fewer species than the 
leaf-eaters and are usually more difficult to control. 

Carbon bisulfid, injected into the soil 
about the roots of cabbage and cauliflower 
plants, with an instrument devised for 
the purpose (Fig. 72), has been success- 
fully used to destroy the cabbage maggot,* 
and may be found useful in other cases. 
Attacks of this insect have also been suc- 
cessfully prevented by surround- 
Jr-' ing the stem of the young plant 
with small cards of thin tarred 
paper. One of these cards, the 
-^ ^o m 1 ^ • tool used for cutting them, and 

Fig. 72. Tool for m- ^ ' 

ifds"fbotr?he°ro'ots''Sf ^^6 manner of using the tool are 
P^^""^^- shown in Figs. 73, 74 and 75. 

310. Burrowers, as the term is here used, include 
not only the so-called horers that burrow within the 
stems and roots of plants, and the leaf miners, that 

* Phorhia brassicce. 




V^' 



Plants as Affected hy Animal Parasites. 175 



Q 



live between the surface of leaves, but also the insects 
that pass their larval stage within fruits. Insects of 
this class are difficult to control, since they are mostly 
beyond the reach of insecticides. 

311. Borers that infest the trunks and main branches 
of trees, may often be kept out by applying strong al- 
kaline washes to these parts. Soft soap reduced to the 
consistency of thick paste by a strong solu- 
tion of washing soda, applied to the trunk 
or branches, forms a rather tenacious coat- 
ing which repels the female insect. Paint- 
ing the trunks of small apple trees a short 
distance above and below the surface of the 
ground w^ith common paint or pine tar, is 
said to prevent the entrance of the round- 
headed borer (306). Protect- 
ing the trunk with straw or 
lath, as recommended to pre- 
vent sun-scald 
(185) may tend 
to keep out 
these insects. 
Borers in the 
trunk can often 




Fig. 73. 



Fig. 74. 



Fig. 75. 
Fig. 73. Card of tarred paper, for placing 
about the stems of young cabbage and cauli- 
flower plants. Reduced one-half. 
Fig. 74. Tool for cutting the cards. 
ha rlaofTTKT^orl h^r ^^^- '^^- Manner of using the tool. The 
ue uehLiuytJU uy dotted lines show the position of the edge of 

probing their *^" '°°^ °" "^" ^^p""- 
holes with a flexible twig. 

312. Leaf -Miners often infest spinach and beets 
grown for greens, rendering the leaves unfit for use. 
For these insects we can offer no preventive measures 



176 Principles of Plant Culture. 

of established value. The application to the young 
foliage of powerful odorants, as coal-tar water or a 
solution of carbolic acid, may prove beneficial. 

313. The Codling-Moth,* which causes so-called 
*' wormy" apples and pears, is controlled by spraying 
the trees at the time of egg deposit, with water contain- 
ing Paris green (284). The first spraying should be 
given as soon as the petals (142) fall, to be followed 
by a second six to ten days later. If much rain falls 
at this season, the sprayings may need frequent repeti- 
tion. A drop of poisoned water should be lodged in 
the calyx (141) of every fruit, and as this evaporates, 
the poison deposited on the skin kills the newly-hatched 
insect as it eats its way inward. 

A band of cloth or paper, placed about the trunk of 
fruiting apple or pear trees forms a convenient retreat 
for larvae of the codling-moth, in which to pupate. 
They may then be readily destroyed by removing the 
band. The bands should be a few inches wide, and 
should be put on before midsummer. They should be 
taken off once in ten to fourteen days, until the fruit 
is harvested, and all cocoons beneath them should be 
crushed. 

314. The Plum Curculio (306) that so often stings 
young plums, causing them to drop before maturity, is 
controlled by jarring the beetles, that deposit their eggs 
in the young fruit, upon sheet-covered frames very 
early on cool, still mornings while their muscles are 
stiff (Fig. 76). The jarring should begin almost as 
soon as the petals (142) fall and should be repeated 
every still morning as long as any beetles are found. 

* Carpocapsa potnonella. 




Plants as Affected hy Animal Parasites. 177 

Any light wood frame, covered with cloth may be used 
as a substitute for the more convenient device shown 
in the figure. Where the substitute is used, the beetles 

must be looked for on 
the sheet and de- 
stroyed as found. 

315. The Prompt 
Destruction of In- 
fested Fruit mate- 

FiG. 76. Curculio catcher. It is wheeled . ,, . -, . , 

beneath the branches of the tree, and riaily aiQS m KCep- 
the latter are struck with a light, cloth- . p -. -, 

covered mallet, which jars the beetles mg the iruit-DUr- 
upon the sheet-covered frame, from 

which they roll into the box beneath. rOWing inSCCts m 
For small trees, the trunk slips in 
through the slot at the left. Subjcctiou. H g S 

and sheep in the orchard are most valuable assistants in 
this work. The apple-maggot* is more effectually con- 
trolled in this manner than by any other known method. 

316. Sucking Insects include many species. They 
feed on the juices of the plant Avhieh they infest, and 
do not directly devour its tissues, as do the eating in- 
sects ; but they reduce its vitality by their continual 
drain upon the reserve food. The so-called scale in- 
sects belong to this class. These are especially difficult 
to destroy, since they are dormant the greater part of 
the year, and in this condition are protected by their 
comparatively resistant scales. 

Sucking insects are net susceptible to poisonous in- 
secticides, hence we must resort to materials that clog 
their breathing pores, as kerosene (294), that dissolve 
their eggs and scales, as potash solutions or that form 

♦ 

* Trypeta pomonella. 



178 Principles of Plant Culture. 

an air-tight coating over them, as the resin washes 
(295).* 

317. The Life Histories of Injurious Insects, which 
can not here be taken up, may profitably be studied by 
the plant grower. A standard work on economic ento- 
mology will furnish the needed information. 

B — Plants as Affected by Vegetable Parasites. 

318. Many of the most serious enemies of cultivated 
plants belong to this class. As a rule, vegetable para- 
sites contain no chlorophyll, and hence are incapable of 
forming their own food. While most of them belong 
to the lower orders of plants, a few species are highly 
developed and produce true flowers and seeds. 

a — By Flowering or phanerogamic (phan'-er-o- 
ga'-mic) parasites. 

Of these, the only ones sufficiently common or inju- 
rious to need mention are the broom rape and the 
dodders. 

319. The Broom Rape of Hemp and Tobacco,t is 
the most injurious species of this class. The seeds ger- 
minate in the soil, and the young plants attach them- 
selves to the roots of their host which they enfeeble by 
robbing them of nourishment. In the case of hemp, 
the parasite also injures the quality of the fibre. 

Preventives. The seed of hemp or tobacco should not 
be taken from a crop infested with broom rape. In- 
fested fields should be planted for several years to 

* The cottony cushion scale, Icerya purchase which was very 
destructive to the orange in California, has been nearly suppressed 
by the introduction of an Australian parasite, the Vedalia cardin- 
alis. 

t Philipoea ramona. 



Plants as Affected hy Fungous Parasites. 179 

some crop not attacked by broom rape, as potatoes, In- 
dian corn, beans, grains or grasses. In infested crops, 
the broom rape should not be permitted to mature its 
seeds. 

320. The Dodders of Clover and Flax,* are the most 
injurious of their class. The young plant attaches it- 
self to the stem of its host, about which it twines, rob- 
bing it of nourishment by means of small suckers. 

Preventives. The seeds of dodder are somewhat 
smaller than those of clover or flax, and hence may 
be separated from the latter by sifting. Badly infested 
ground should be devoted for two to four years to a 
crop not attacked by the dodder. 

b — Plants as affected by fungous parasites. 

321. The Fungi constitute an extensive class of 
plants that derive their nourishment wholly from or- 
ganic matter. Many of them are injurious to culti- 
vated plants. Unlike the harmful insects, most of which 
work their ravages within full view, the fungi are in 
many cases discernible only with the microscope, 
and reveal their presence only by the death or injury 
of their host. The fungous parasites are very numer- 
ous and exhibit great diversity of structure and habit. 
Some of them live only upon enfeebled plants, while 
others attack healthy ones. Some, as the pea mildew, 
grow upon the surface of their host, drawing their 
nourishment through the epidermis ; others, like the 
peach curl and oat smut, grow within the tissues of the 
plant upon which they feed. All of the latter class 

* Cuscuia trifolia, C. Epilinum 



180 Principles of Plant Culture. 

send their fruiting parts to the surface of the host 
plants to disseminate their spores in the open air. 

The fungi multiply from extremely minute spores 
(52) that are produced in immense numbers, and when 
mature, are very readily blown about by wind. Many 
of them also multiply from thread-like organs called 
hyphae (hy'-phge), something in the same manner as 
Canada thistles multiply from their roots. 

322. Methods of Controlling Fungi are of three 
classes : 

a— Removing and destroying the affected parts; 
b — Preventing the germination of the spores ; 
c — Destroying the fungus itself by applying some 
destructive material (a fungicide (fun'-gi-cide) ). 

323. Destruction of the Affected Parts is the most 
effectual prcA^entive known in cases where the fungous 
disease attacks a portion of the plant whence it spreads 
to the remaining parts, as in the black knot of the 
plum,* the blight of the pear, apple and quince, f the 
red rust of the raspberry and blackberry, | and the 
corn smut.§ 

The affected part should be removed as scon as dis- 
covered and burned at once, to destroy any spores of 
the fungus it may contain or which might mature later. 
It is generally important to cut the diseased branch 
some distance below the point of visible infection, as in 
many cases the mycelia of the fungus extend farther 
than external appearances indicate. 

* Ploivrightia morbosa. \ Miornccocuf! annilovorus. 
X Coeonia lumina'um. ^, Untilago Maydit. 



Plants as Affected hy Fungous Parasites. 181 

324. Preventing Spore Germination is the only 
known method by which we can combat the fungi de- 
veloping within the host plant {endophytic (en-do- 
phyt'-ic) fungi). 

In fungi that develop from spores planted with the 
seed, as the smuts of the small grains, spore germina- 
tion may be prevented by treating the seed with a solu- 
tion of certain chemicals or with hot water. Of the 
former, formalin is now most used, and unquestionably 
destroys the spores of the smut, and while it has gen- 
erally been found to injure more or less the germina- 
tion of the seed, it is now recognized as the most effi- 
cient and practical method of treating seed for the 
prevention of smut in wheat, oats and barley. 

325. The Formalin (formaldehyd) Treatment con- 
sists in immersing the seed in a solution of formalin 
in water. To treat seed oats for the prevention of 
smut prepare a solution of one pound (pint) of forty 
per cent formaldehyd (formalin) in thirty-six gallons 
of water. The seed should be submerged in this solu- 
tion for ten minutes and then spread on a canvas or 
floor to dry. 

For the treatment of barley seed for the prevention 
of smut use one pint of formalin in twenty gallons of 
water. 

326. Fungi that Develop from Spores Surviving 
the Winter In or Upon the Soil, as the onion* smut, 
cannot be prevented by disinfecting the seed. For this 
disease a mixture of flowers of sulfur and air-slaked 



* Eurocystis Cepuloe. 



182 



Principles of Plant Culture. 



lime, sown with the seed, has proved beneficial by pre- 
venting infection of the young plant. 

327. Fungi the Spores of which Survive the Winter 
Within their Dead-Host Plants, as in the club-root of 
the cabbage* and turnip, and the onion mildew,t may 
be held in check to some extent by burning the fungus- 
killed plants at the close of the season. 

328. Fungi that Infect their Host from Spores 
Deposited On the Aerial Parts of the plant, as the 
scab of the apple| and pear, and the downy grape-vine 
mildew§ may be held in check by applying a fungicide 
(321) to the host plant, to destroy the spores as they 





.^^.VClJ-Is: 



Fig. 78. A scab spot mag- 
nified. (After Trelease.) 




Fig. 77. Apple affected with 
scab (the dark spots), Fusicla- 
dium dendriticum. (After Scrib- 
ner.) 



Fig. 79. Section through a 
scab spot, highly magnified. 
The egg-shaped parts at the 
right are the spores. (After 
Trelease.) 



alight upon it. Various compounds of copper and of 
sulfur are destructive to the spores of fungi, and when 
properly applied, are harmless to the plant. The cop- 



* Plasmidiophora Brassicce: 
X Fusicladiuni dendriticum. 



t Peronospora Schleideniana. 
i Peronospora viticola. 



Plants as Affected hy Fungous Parasites. 183 

per compounds are more generally satisfactory, since 
they have the greater adhesive power. 

329. The Bordeaux Mixture, which consists of a 
compound of copper sulfate (324) and lime, is now ex- 
tensively used to prevent many fungous diseases of 
this class. A standard formula for the Bordeaux mix- 
ture is : 

Dissolve 5 pounds of copper sulfate in 25 gallons of 
water by suspending it in a bag of coarse texture near 
the surface of the water; slake 5 pounds of fresh quick- 
lime in sufficient water to form a paste and dilute to 
25 gallons. Pour the two solutions together. 

Metal vessels, other than those of brass or copper, 
should not be used. 

Prepared by the above formula, the Bordeaux mix- 
ture often contains more lime than is needed for the 
chemical action that occurs. To avoid this excess of 
lime, a chemical test may be used, as follows : Pour 
only halt of the slacked lime and water into the cop- 
per-sulfate solution, stir well, and add a few drops of 
a 20 per cent solution of potassium ferrocyanid. If a 
rich, reddish-broT\Ti color is produced, add more lime. 
Continue to test and add lime until the reddish-brown 
color no longer appears. Then add a little more lime, 
as a slight excess of lime is desirahle. A bright, clean 
knife blade may also be used as a test. If a slight film 
of copper forms upon it when placed in the mixture, 
more lime is needed. The Bordeaux mixture is prefer- 
ably strained before use, and should be kept well stirred 
during its application (304). It may be applied with 
any good spray pump. 



184 Principles of Plant Culture. 

The arsenical compounds (283) may be added to the 
Bordeaux mixture, and thus a single treatment will 
serve for both insects and fungi. 

330. The Diseases Preventable by Bordeaux Mix- 
ture are the apple and pear scab (328), the downy 
mildew and black rot* of the grape, the earlyf and 
late blightl of the potato, the gooseberry mildew, § the 
leaf-blight of the pear** and some others. 

In all these diseases, however, the treatment is pre- 
ventive rather than curative. The first application 
should be made before the disease appears and should 
be followed occasionally by others as new foliage is 
formed or as the material is washed off by rains. 

331. Ammoniacai Solution of Copper Carbonate 
possesses nearly the same fungicidal properties as Bor- 
deaux mixture, but adheres less strongly to foliage. 
Being a solution, it requires no straining or stirring, 
and it leaves less stain on drying than Bordeaux mix- 
ture, which makes it preferable to the latter for use 
upon plants of which the fruit is nearly mature. To 
make this solution, dissolve one and one-half ounces of 
precipitated copper carbonate in one quart of strong 
commercial ammonia, and add 25 gallons of water. 
The ammonia should be procured in a glass or earthen 
vessel, which should be kept tight ^y corked. To pre- 
vent waste of the ammonia by evaporation, prepare im- 
mediately before spraying. 

332. Potassium-Sulfid Solution is used to some ex- 
tent to prevent gooseberry mildew (330), and a few 

* Lcestadm BidwelUi. \ Macrosporium, Solani . % Phytophthorainfestans^ 
^ Sphoerotheca Morsuvce. ** Entomosporium maculatum. 



Plants as Affected hy Fungous Parasites. 185 

other diseases, but it is less enduring in its effects than 
the copper compounds. To prepare it, dissolve one- 
half ounce of potassium sulfid ( sulfur et of potassium, 
liver of sulfur) in one gallon of Avater and apply im- 
mediately. The sulfid is best dissolved in a little warm 
water and then diluted. 

333' Moisture Favors Spore Germination, hence a 
free circulation of air through the orchard and vine- 
yard tends to prevent fungous diseases by absorbing 
excessive moisture (226). Branches of fruit trees should 
not be permitted to hang near the ground, and weeds 
should be kept down. 

Grapes are sometimes inclosed in paper bags on the 
vine, to keep them dry, and thus preserve them from 
fungous attack. Grape vines sheltered from rains by a 
cornice are seldom much troubled with fungous diseases. 

334. Fungi that Develop chiefly on the Outside of 
the Plant {epiphytic (ep-i-phyt'-ic) fungi), are as a 
rule readily controlled by sulfur, either in the form of 
flowers of sulfur, or the solution of potassium sulfid 
(332). To this class belong the powdery mildews of 
the grape,* apple,t etc. 

335. The Cultivator will often Need to Consult the 
Specialist in dealing with fungous diseases. In many 
cases, it will be difficult or impossible for him to decide 
as to the exact nature of a given trouble without train- 
ing and skill in the use of the compound microscope. 
Specialists in this line are now employed by the govern- 
ments of most civilized nations and by many agricul- 
tural experiment stations, and they should be freely 

* Uncinula spiralis. f Podosphcera oxycanthoe. 
13 



186 Principles of Plant Culture. 

consulted. Much may be learned, however, by studyina^ 
the best books on the subject. The cultivator should 
be able to recognize the principal fungous diseases. 

Section VIII. Plants as Affected by Weeds 

336. Weeds are plants of the higher orders that per- 
sist in growing where they are not wanted. They in- 
jure the desirable plants about which they grow by 
robbing them of light, moisture and food, and their 
presence is an evidence of slovenly culture. The re- 
markable vigor and prolificacy possessed by many weeds 
would enable them to soon overcome most cultivated 
plants, but for the aid of the cultivator. As with 
harmful insects and fungi, prompt and persistent ef- 
forts are essential to the control of weeds in most cul- 
tivated grounds. 

337. Annual, Biennial and Perennial Weeds. With 
reference to their term of life, weeds and other plants 
are divisible into three classes, viz., annual ^ those that 
live but one season; hiennial, those that live only two 
seasons; and perennial, those that live an indefinite 
number of seasons. Weeds of the first class usually 
seed most abundantly, and hence they are most mdely 
distributed and appear in cultivated grounds in the 
greatest numbers. Those of the third class are com- 
monly most tenacious of life and are therefore often 
most difficult to control. 

338. Annual and biennial weeds, since they have a 
definite life period and multiply almost exclusively by 
seed, may be controlled by preventing seedage. To ac- 
complish this with certainty, the plants should be de- 



Plants as Affected by Weeds. 187 

stroyed before bloom, as many species possess enough 
reserve food to mature seeds sufficiently for germina- 
tion, if cut while in flower. 

339. Perennial weeds often multiply by suckers as 
well as by seeds (Fig. 80). Since the roots or under- 
ground stems whence the suckers grow (114), are hid- 




FiG. 80. Showing- how plants of the sow thistle multiply from 
underground stems. 

den beneath the soil and are often extremely tenacious 
of life, weeds of this class are frequently very hard to 
eradicate. Persistent prevention of leafage, by starv- 
ing the protoplasm of the roots, is always effectua], 
though it is often very difficult to carry out, since the 
suckers of some species grow with great rapidity. Yet, 
on the whole, no better remedy is known. Frequent 
plowing and cultivation of the infested ground is usu- 
ally the most effectual means of preventing leafage. 

Certain very tenacious perennial weeds, as the Can- 
ada thistle* and the sow thistle,t when growing on 
deep, rich loams in which the roots spread freely below 
the plow line, may, it is said, be crowded out by seed- 
ing the land to grass, at less cost than they can be 
subdued by the plow. 

* Cnicus arvenns. f Sonchus arvnsis. 



188 Principles of Plant Culture. 

If we have mastered the foregoing chapters, we are 
now prepared to enter upon a more advanced stage of 
culture, and to learn how to cause new plants to grow, 
and how to treat the plants thus grown that they may 
best serve oiir purpose. 



The following books are recommended for reading, 
in connection with the preceding chapter : Elementary 
Meteorology, "Waldo; Chemistry of the Farm, Waring- 
ton; The Spraying of Plants, Lodeman; Economic En- 
tomology, Smith; Fungous Diseases of the Grape and 
Other Plants, Lamson-Scribner ; American Weeds and 
Useful Plants, Darlington. 



CHAPTER IV. 

PLANT MANIPULATION. 

Section I. Plant Propagation. 

340. Propagation, as the term is generally used in 
plant culture, is the artificial multiplication of plants, 
i. e., reproduction (16) encouraged or induced by the 
knowledge, skill and care of the cultivator. 

Theoretically, any part of a plant containing living 
cells, with sufficient prepared food or tissue capable 
of preparing food (58) may under proper conditions 
develop into a complete plant. But in practice, we have 
not been able to fully demonstrate this theory; for ex- 
ample, the roots and leaves of some plants have not 
been induced to form buds. 

341. Plants are Propagated by Numerous Methods, 
but only two of these are distinct in kind, viz., by seeds 
(or spores), and by division of the plant. In propaga- 
tion by seeds, the embryo of the seed (53) is the vital 
center whence the new plant is developed. In propa- 
gation by division, a living bud (127) from the parent 
plant, or a bit of tissue capable of forming a bud, is 
substituted for the embryo of the seed. In seed propa- 
gation, the resulting plant is the product of sexual 
fecundation (149), and hence cannot be considered as 
strictly a part of the parent only. It does not necessar- 
ily resemble the parent closely. In propagation by di- 
vision, on the other hand, the resulting plant may be 



190 Principles of Plant Culture. 

regarded as simply a continuation of the growth of the 
parent in a new location, and generally closely resem- 
bles the parent. 

342. Propagation by Seeds is commonly practiced 
with annual and biennial plants and with perennials in 
which the reproduction of the exact parental form is 
unimportant, as in the cereals, forest trees and seedlings 
intended for grafting. This method is also used when 
variation in the progeny is desired, as in developing 
new varieties (438 b). 

343. Propagation by Division of the plant is used 
when it is desired to reproduce the exact parental form, 
as in fruit- and the finer ornamental trees, many flower- 
ing plants, etc. ; in certain plants that are more readily 
multiplied by division than by seeds, as mint and many 
other perennial herbs; and in other plants that rarely 
or never produce seed, as the horse-radish, sugar cane, 
banana, etc. 

A — Propagation by Seeds. 

344. This is the most common method of propagating 
plants. It seemed appropriate to give nearly all of the 
needed directions for planting seeds in the first two sec- 
tions of Chapter 11. We add, therefore, only a few 
general rules deduced from the principles there stated. 

a — The soil in which the seeds are to he planted should 
he thoroughly crumhled, because the seeds must have 
access to the oxygen of the air, or they cannot germi- 
nate (31). 

h— The well-crumhled soil shotdd he compactly pressed 
ahoiit the seeds, because the seeds cannot absorb moist- 



Propagation hy Division. 191 

ure rapidly unless the seed-case is in contact with the 
moist soil particles at many points (27 b). 

Q—The soil sJiould he moist, hut not wet enough to 
puddle (31) ; otherwise the oxygen is likely to be shut 
out from access to the seeds (34). 

d — Seeds should he planted no deeper than is neces- 
sary to insure the proper degree of moisture; otherwise 
the plantlet expends a needless amount of energy in 
reaching the surface (50, 47). Very small seeds should 
be only slightly covered, if at all, and must receive ar- 
tificial watering when necessary (51). Spores must not 
be covered with soil at all (52). 

B — Propagation by Division. 

345. We have seen that a part of a plant, placed un- 
der favorable conditions, is usually capable of develop- 
ing a complete plant (340). A section or cutting of 
the stem, for example, that has no roots at the time it 
is cut off, may be caused to form roots, and thus be- 
come a complete plant. A cutting of a root may also 
put forth a bud, which in turn may develop into a 
shoot, and form leaves, flowers and fruit. Again, we 
have seen that portions of cambium from different, 
nearly-related plants may unite by growth (69), which 
enables us to change undesirable sorts into valuable 
ones by grafting (383). These and certain other meth- 
ods of multiplying plants, come under propagation by 
division. 

In propagation hy division, the presence of at least 
one healthy growing point (66) in the part selected for 
the propagation is generally essential to success and is 
always helpful. 



192 Principles of Plant Culture. 

The processes treated in this and the two succeeding 
sections may be likened to surgical operations in medi- 
cine. If plants are less highly organized and possess 
less of sensibility than the higher animals, they are, 
none the less, living beings. Violent operations, if nec- 
essary, should always be performed with this truth in 
mind. Needless injury and careless Imndling in tlif 
treatment of plants are always to he avoided. 

346. Two Methods of Propagation by Division may 
be distinguished, viz., by parts intact and detached 
parts. In the first, the part selected for propagation is 
not separated from the parent until the organs needed 
to make it self-supporting are formed; or if a cion 
(386), until it has united to the part on which it is in- 
tended to grow. In the second method, the part in- 
tended for propagation is severed from the parent at 
the outset and placed under conditions favoring the for- 
mation of the organs needed to make it self-supporting ; 
or if a cion, favoring its union with the stock (383). 

A— PROPAGATION BY PARTS INTACT. 

This method is applicable to many plants and has the 
advantages of being reliable and requiring little skill. 
The part selected for propagation, being nourished by 
the parent until it forms the needful organs, is able to 
endure unfavorable conditions that would prove fatal 
in most other methods of propagation. This method in- 
cludes four divisions, viz., propagation by suckers 
(347), by stolons (348), by laye7^s (349), and by ap- 
proach grafting (399). In the first two, the propaga- 
tion is performed by the parent plant without other 



Propagation hy Parts Intact. 



193 



aid than the maintenance of a well-aerated, moist and 
clean soil that stimulates the production of the needed 
organs, which in these cases are roots. 

347. Propagation by Suckers. Suckers are shoots 
that originate from roots or underground stems and 
grow upward, forming young plants about the parent, 
as in the blackberry, plum, choke-cherry, etc. The propa- 
gation consists in simply cutting off the root or under- 
ground stem whence the sucker proceeds, and trans- 
planting the latter. 

The grow^th of suckers may generally be stimulated in 
plants that naturally produce them, by cutting off the 
roots or underground stems from which they grow, or 
by severely pruning the top. 

■ The propagation of woody plants from suckers is not, 
as a rule, considered ^^dse, since the roots are usually 
poorly developed in proportion to the stem, and some 





Fig. 81. 

Fig. 81. Sucker plant of the red raspberry. Rubus strigosus. 
A, before growth has strated; B, after. The two shoots of B 
starting just above the roots form the new canes. 

Fig. 82. Tip plant of black raspberry. The bud, whence the 
young shoot starts, appears at the base of the present cane. 
(After Bailey.) 

plants grown in this manner seem to acquire the ten- 
dency to form suckers excessively. In the red rasp- 



194 Principles of Plant Culture. 

berry* and the blackberry,! however, propagation by 
suckers is the most convenient method, and it appears 
to be followed by no bad results (Fig. 81). 

348. Propagation by Stolons. A stolon is a branch 
that starts above or at the surface of the ground and 
either grows prostrate or curves downward till it reaches 
the ground where it takes root, usually at the nodes 
(115). The currant, juneberry, cranberry and many 
herbaceous plants are readily multiplied in this way. 
Stolons often root without assistance, but the rooting is 
much hastened and encouraged by covering the branch 
with soil. When well rooted, the young plants may be 
separated from the parent by cutting the stolons. 

Woody plants grown from stolons are seldom uniform 
in size and are not often as well rooted as those grown 
from cuttings (358). Some herbaceous plants are, how- 
ever, more readily propagated by stolons than by any 
other means. 

The offset by which the houseleekj is so readily prop- 
agated, is a very short stolon that forms a single tuft of 

leaves at its apex. 
The cane of the black- 
cap raspberry, § which 
roots from the tip (Fig. 
82), and the runner 
of the strawberry 
(Fig. 83), that forms 

Fig. 83. Runner of the strawberry. a plant at Cach alter- 
nate node, are modified stolons. 




* Ruhus sfrigosHs, R. Idceus. f R. viUosus. 
XSenipervwim. I Ruhus occidentalis. 



Propagation hy Parts Intact. 195 

349. Fropagation by Layers or Layering. The 

layer is an artificial stolon, i. e., a branch that does not 
naturally grow downward, which is covered with or 
surrounded by moist soil to stimulate the production of 
roots (88). The branch may be bent down and cov- 
ered, as is usally practiced with the grape, wistaria, 
etc., or the soil may be ridged up about the branch, as 
is done with the quince and paradise apple. In either 

case, the terminal portion of 
-4^^W ^^^ stem is commonly left 

uncovered. In the latter 
%yi^ ^ '-^ method, which is known as 




f?.^f;r.^ ^^"^ tnound-layenng, (Fig. 84), 

'J^'^Sr^/*^^---^"^.-'^. the stems of the plant to be 

^Jss^w.\?- -~ - - •' "" layered are usually cutoff 

Fig. 84. Mound-layering of just aboVC the SUrface of 
gooseberry plants. (After Bai- 
ley.) the ground in early spring, 

to stimulate the formation of vigorous shoots, which 
are ridged up about midsummer or preferably not until 
the succeeding fall or spring. The ridging should be 
sufficiently high to cover several of the lower nodes 
(115). Roots grow out at the nodes and the shoots arc 
usually well rooted by the autumn following the ridging. 
Many woody plants that do not readily form roots 
when layered, may be induced to do so by mutilating 
the stem somewhat in the covered part. This tends to 
restrict the growth current (79) and causes an accu- 
mulation of reserve food, from which roots may grow. 
Girdling, twisting, bending or splitting the stem for a 
short distance will often have the desired effect 
(Fig. 85). 



196 



Principles of Plant Culture. 




Layering is a very reliable and expeditions method of 
propagating many woody and herbaceous plants. 

350. Propagation by Division of the Crown of the 
plant, which is practicable with many perennial herbs, 

as the rhubarb, dahlia, globe artichoke, etc., 
though not strictly analogous to propagation 

by stolons or layers, 
may be considered 
here. It consists in 
taking up the plant, 
preferably while doj'- 
mant, and cutting the 
crown into two or 
more parts, according 
to its size or the num- 

FiG. 85. Layered branch of cur- bcr of plants desired, 
rant, split to encourage the forma- ^ 

tion of roots. and planting the divi- 

sions as separate plants. This method is applicable to 
propagation for private use, rather than for sale pur- 
poses. 

Propagation by approach grafting, although in order 
here, is more readily treated with the other methods of 
grafting (399). 

B— PROPAGATION BY DETACHED PARTS. 

This comprises two different modes of propagation, 
viz., by specialized huds and by sections of the pla^it. 

a — Propagation by Specialized Buds. 

351. This includes propagation by hidhs, hulhlets, 
corms and tubers. It is in a sense intermediate be- 
tween propagation by parts intact (346) and by cut- 



Propagation 'by Detached Parts. 



197 



tings (358). The bud that is to form the future plant, 
though not having roots of its own, has been specially 
prepared by the parent, through an abundant food 
supply and a partially dormant condition of the proto- 
plasm, to maintain a separate existence, even under 
adverse conditions, and in due time to develop into a 
plant. In these respects it resembles a seed, from which 
it differs, however, in the less dormant condition of its 
protoplasm and in not being the product of sexual fec- 
undation (341). 

352. The Bulb is a very short stem containing a ter- 
minal bud inclosed in scales (127). The scales are 
(^^ thickened by a store of food, and in 

their axils are smaller lateral buds. 
The terminal bud usually develops 
into a flower and then perishes. One 





Fig. 86. Fig. 87. Fig. 88. Fgi. 89. 

Fig. 86. Bulb of the common onion, Allium cepa, divided 
lengthwise. B, buds. 

Fig. 87. Bulb of garlic, Allium sativum. It contains several 
smaller bulbs (cloves). 

Fig. 88. Bulb of wild lily. 

Fig. 89. The same divided lengthwise, showing buds, B. 

or more of the lateral buds may develop into flower - 
buds for the next year and thus continue the life of 
the plant, as in the common onion (Fig. 86) ; or the 
lateral buds may develop at the expense of the parent, 
as in the potato onion. 



198 



Principles of Plant Culture. 




Fig. 90. Bulblets in axils of leaves of 
tiger lily. 



353. Bulblets or Bulbels are small bulbs formed in 
the axils of the leaves in certain plants, as the tiger 

lily,* (Fig. 90), or 
at the apex of the 
stem, as in the 
''top" or bulb-bear- 
ing onion (Fig. 91). 
354. The Corm 
(Fig. 92) differs 
from the bulb chief- 
ly in being without scales. The food is deposited in 
the thickened stem. The corms of our flowering plants, 
as the crocus, cyclamen, etc., are generally called bulbs 
in commerce. 

355' The Tuber, of which the common potato is the 
most familiar example, differs from the corm in being 
the end of an underground branch of 
the stem (114), instead 
of developing in direct 
contact with the par- 
ent. It also has more 
numerous buds (eyes) 
than the corm. 

356. Propagation 




Fig. 
lets 
onion, 
used 
"sets. 



91. 
of 



Bulb- 
"top' 



Fig. 92. Corm of 
someti'-mes S?ms'' Tbuds)'"'for from Bulbs, Bulblets, 

following year. Qorms and Tubers is 
a very simple operation and consists merely in planting 
these parts in the place where the plants are desired. 
Tubers may be cut into pieces containing one or more 
buds each, if desired. The rules given for planting 
seeds (344) apply equally well here. All should be 

* Lilmm tigrinum. 



Propagation hy Detached Parts. 199 

stored for preservation in a cool, moderately dry place, 
that is free from frost. They retain their vitality but 
a single year. 

In the methods of propagation thus far considered, 
with the sole exception of layering (349), advantage 
has been taken of a natural mode of plant multiplica- 
tion. The skill of the cultivator, however much it may 
assist the processes, is not necessary to their success, 
since wdld plants habitually increase by the same meth- 
ods. We will now consider a method which is less often 
illustrated in nature, and in which the skill and care of 
the cultivator are, as a rule, essential to its accomplish- 
ment, viz: 

b — Propagation by sections of the plant. 

The various methods of propagation in this division 
are alike in the fact that a detached part of the parent 
plant, containing living protoplasm, is placed for a time 
under specially favorable conditions, in virtue of which 
the part is enabled not only to live, but to perform its 
functions and reproduce the needed organs ; or if a cion 
(386), to unite by growth to the part with which it is 
placed in contact. 

357. In propagation by sections of the plant we must, 
of necessity, wound the plant tissues in securing the 
parts for propagation. Since it is alwaj^s desirable that 
the wound should heal promptly (72), it is important 
that the cutting tools used shoidd have sharp and 
smooth edges. 

As here considered, propagation by sections of the 
plant includes two methods, differing materially in 



200 Principles of Plant Culture. 

their requirements and in the manner of development 
of the plants, viz., propagation by cuttings and by 
grafti^ig. 

8l— Propagation hy Cuttings. 

358. A Cutting is a detached member of a plant, in- 
tended to be placed in the soil or some other medium 
for propagation. It may be in an active or a dormant 
state (13), and may or may not contain* a growing 
point {Q^). Before the cutting can become a plant, it 
must develop the essential part or parts of the plant 
that it lacks; i. e., the stem and the leaves, or the root, 
or all these members. Cuttings of the stem are usually 
planted with their proximal end (115) in the soil, and 
their distal end in the air. Root cuttings are generally 
covered in the soil. 

359. Nearly All Plants may be Propagated by Cut- 
tings from one or another of their parts. The ease 
with which plants may be multiplied in this way varies 
greatly in different species (21), and even in different 
varieties of the same species. The appearance of a 
plant does not always indicate the facility with which 
it may be grown from cuttings ; the only sure way to 
ascertain this is by trial. 

Climate exerts a marked influence upon the ten dency 
of plants to develop from cuttings. In certain loca- 
tions in southern Europe and in parts of South Amer- 
ica, branches of the common apple tree, sharpened and 
driven into the ground as stakes, often take root and 
sometimes even bear fruit during the same season. A 



Propagation by Cuttings. 201 

warm, moist atmosphere is very favorable to propaga- 
tion by cuttings. 

We have seen that the roots of certain plants nor- 
mally develop buds (130). In like manner, the stems 
of many plants, as the potato, grape, etc., normally 
develop growing points of roots at their nodes (115). 
Plants that normally develop buds upon their roots, 
or growing-points of roots at their nodes, are readily 
propagated hy cuttings. But propagation by cuttings 
is not limited to such plants (362). 

360. The Essential Characteristics of a Cutting 
are a— a certain amount of healthy tissue; 5— a certain 
amount of prepared food, or of tissue capable of pre- 
paring food (58) ; c — in mcst species, a growing point 
[^^) , either of the stem or root, or of both. 

361. The Parts of plants to be Used for Cuttings, 
therefore, are preferably the younger, matured growths, 
since the tissues cf these are most vigorous ; or else a 
part that possesses a certain amount of healthy an<l 
vigorous leaf tissue. The cutting should always con- 
tain one or more buds when practicable (127). 

362. Conditions that Favor the Growth of Cuttings. 
a — A soil warmer than the air aitove it ("bottom 

heat") is important in growing many plants from cut- 
tings. Warmth stimulates plant growth, and when ap- 
plied to one part of a plant, it stimulates growth in 
that part. If the soil about a planted cutting is warmed 
to a temperature considerably higher than that of the 
air above, the growth of roots is stimulated. Indeed 
bottom heat often excites groAvth in cuttings that will 
not grow without it. 

14 



202 Prhiciples of Plant Culture. 

b — A comparatively low air temperature is import- 
ant in growing many plants from cuttings of the stem 
(377), because it is essential that the stem growth be 
held in check until roots are formed. A soil tempera- 
ture of about 65° F., with an air temperature about 
fifteen degrees lower, is suited to the great majority of 
plants usually propagated under glass from cuttings. 
It is important that these temperatures be maintained 
nearly constant until roots have developed. 

Since we have better facilities for raising than for 
lowering the natural temperature of the atmosphere, 
propagation from cuttings is easiest at a time of the 
year when the temperature of the atmosphere during 
the day does not much exceed 50°. By observing spe- 
cial precautions, however, it is possible to propagate 
many plants from cuttings during the warm season. 

a— Abundant moisture is important in growing plants 
from cuttings, because moisture favors root develop- 
ment (88), and water is essential to cell growth (62). 
The amount of water required varies considerably with 
different plants and conditions. 

With cuttings ccntaining leaf tissue (377, 382), 
transpiration (74) must be reduced to the minimum 
until roots are formed, because water cannot be taken 
up freely without root-hairs (100). For such cuttings, 
therefore, the air as well as the soil must be kept 
abundantly moist (369), and the direct rays of the sun 
must be intercepted by shading (235). 

363. Methods for Controlling Temperature. The 
alternations of temperature in the open air are un- 
favorable to the development of cuttings, though many 



Propagation by Cuttings. 



203 



plants, as the willow, grape and currant, are readily 
propagated from cuttings out of doors. Some struc- 
ture, therefore, that may confine warmth radiated from 
the earth or artificially generated, or that may when 
necessary shut out a part of the solar heat, is always of 

great assistance 
i n propagatim^ 
plants from cut- 
tings, and in 
many species is 
essential to suc- 




FiG. 93. Cold-frame, 
ventilation. 



with sash lifted for 



cess. Since light 
is necessary to food preparation (58), such a structure 
must be roofed with glass or some other more or less 
transparent material. 

364. The Cold-Frame (Fig. 93) is the simplest struc- 
ture of this kind. It consists of a frame or box with- 
out bottom, usually shallower on one side than on the 
other, covered with glazed window sash.* The frame 
is generally placed so that its shallower side faces the 
south, thus giving its cover a southward slope. It has 
no provision for artificial heat, though when covered 
with glass, the temperature within the frame is much 
increased during sunshine, owing to the property pos- 
sessed by glass for confining the heat rays. The cold- 
frame should be protected in freezing weather by an 
additional cover of mats or blankets, while excessive 
sun heat should be avoided by shading (235). Muslin- 
or paper-covered frames require no shading. 

* Muslin or paper is sometimes used instead of glass, and these 
materials may be rendered waterproof and less opaque by paint- 
ing with linseed oil or some similar material. 



204 



Principles of Plant Culture. 



Although affording no bottom heat (362 a), the cold- 
frame may be used for propagating many plants from 
cuttings. It is also serviceable in connection with the 
propagating bed (368) for "hardening off" young 
plants grown from cuttings in the latter, as well as for 
growing many plants from seed. Set over a pit in the 
earth, the cold-frame makes an excellent place (cold 
pit) for wintering half-hardy plants. 

365. The Hotbed differs from the cold-frame in hav- 
ing bottom heat (362 a), which is usually supplied by 
the fermentation of moist vegetable material, as horse 
manure, leaves, refuse hops or tan bark. The material 
intended for heating, if fresh, should be thrown into 
a pile of sufficient size to generate heat several days 
before it is desired for use ; and unless already moist, 
it should be moderately sprinkled with water. In or- 
der that all the material may reach the same stage of 
fermentation, the mass should be made into a new pile 
after the heating starts vigorously, as is indicated by 

vapor rising 
from the heap. 



and the outer 
part of the mass 
\ should be placed 
in the center of 
the new pile. 

Fig. 94. Cross-section of hotbed in pit. The LeaveS ferment 
frame Is banked up a little with earth. (After 

Greiner.) slower than the 

other materials above named, and hence may often be 
advantageously mixed with them to lengthen the period 
of fermentation. 




Propagation hy Cuttings. 205 

Heat is economized by placing the fermenting mate- 
rial in a pit in the ground, but hotbeds are often made 
above ground. The hotbed pit should be in a well- 
drained and sheltered place, and two to two and one- 
half feet deep. In this the heating material shuuld be 
moderately packed, until the pit is nearly or quite full. 
The frame may then be placed over the pit, after which 
the heating material should be covered with soil and 
the sash put on to confine the warmth. Within a few 
days after covering with the sash, the fermenting mate- 
rial usually generates a rather violent heat, which 
should be permitted to decline to about 90'^ F., before 
planting seeds or cuttings in the hotbed. The same 
protection against excessive heat or cold is used as for 
the cold-frame ; but the hotbed requires much more care 
in ventilation, since the heating material generates 
vapor and carbonic acid as well as heat, and these when 
present in excess are detrimental to plant growth. 

366. The Greenhouse is an expansion of the hotbed, 
i. e., a structure sufficiently large so that it may be en- 
tered, and arranged for heating by fire.* In temperate 
climates, greenhouses are usually constructed 12 to 22 
feet wide, with a gable or M roof, having a slope of 35^ 
to 40°, covered with glass and with the ridge or ridges 
extending north and south (Fig. 95) ; but in very cold 
climates a shed roof facing the south is preferable. 
Greenhouses are often built with one slope of the roof 
longer and less steep than the other, and with the ridge 
extending east and west. Such a roof is called a "two- 
thirds" or "three-quarters span," according as the 

* Hotbeds are now being heated by fire to some extent. 



206 



Principles of Plant Culture. 



longer slope covers two-thirds or three-quarters of the 
width of the house. The long slope usually faces the 
south, but houses have recently been built with the 
shorter and steeper slope facing the south, a plan 
thought to possess advantages for growing pertain 
plants, as carnations. 

Provision is made for ventilation in glass houses by 
placing a certain number of movable sash in the roof or 
elsewhere. In order that the glass may not be far above 
the plants, the side walls should not exceed five feet in 
height (240). These may be cf wood, but a wall of 
brick, ten inches thick, with a two-inch air space in the 




Fig. 95. Cross-section of greenhouse. (After Greiner.) 

center, is preferable, since this better economizes heat. 
The furnace and potting rooms obstruct the light least, 
and afford the most protection, when located to form 
the wall opposite to the sun. In houses extending north 
and south, the south end is usually glazed above the 
height of the side walls. 

367. Heating Devices for the Greenhouse are of 
various kinds. The "smoke flue" is simplest and cheap- 
est in first cost. It consists of a flue extending from the 
furnace, which is placed somewhat below the floor level, 
lengthwise through the house, preferably rising gradu- 
ally to a chimney at the opposite end; or the flue may 



Propagation hy Cuttings. 207 

cross the farther end of the house and return at the 
other side, to a chimney built directly upon the furnace. 
The latter method usually gives better draft, since the 
warmth from the furnace stimulates an upward current 
of air through the chimney. The flue should be of brick 
for the first 25 feet from the furnace, as a safeguard 
from fire. After this it may be of cement, or of vitri- 
fied drain-pipe. 

Greenhouses of the better class are now almost in- 
variably heated with steam or hot water, or with a com- 
bination of the two. Pipes from a boiler located be- 
neath the floor level, extend nearly horizontally about 
the house, below the benches, returning to the boiler ; or 
the main feed pipe extends overhead to the farther end 
of the house, where it connects with a system of return 
pipes beneath the benches. While the steam- or hot- 
water heating costs much more at the outset than the 
smoke-flue system,* it is generally found not less eco- 
nomical and far more satisfactory in the long run. 
Where the pipes need to make many turns, steam is 
usually more satisfactory than hot water. 

368. The Propagating Bed. A certain part of the 
greenhouse is usually set apart for propagating plants 
from cuttings. The propagating bed is made upon the 
ordinary greenhouse bench, directly over the flue or 
heating pipes. To furnish the bottom heat (362 a), the 
space beneath the bench is boxed in with boards. Hori- 
zontal doors are, however, provided which may be 



* In round numbers, the cost of the smoke-flue may be esti- 
mated at ten per cent of the whole outlay required in a house 
heated by this method, while in one heated with hot water or 
steam, the cost of the heating apparatus is not far from fifty 
per cent of the whole. 



208 Principles of Plant Culture. 

opened when it is desirable to allow a part of the heat 
to pass directly into the house. The floor of the bench 
should not be so tight as to hinder drainage. 

In large commercial establishments, entire glass 
houses are often devoted solely to propagation. Such 
houses are usually eleven or twelve feet wide, with low 
side walls. Sometimes lean-to houses are built for 
propagation, on the north side of a wall, where direct 
sunlight is cut off. 

In making the propagating bed, a thin layer of sphag- 
num moss is usually spread over the floor of the bench 
and covered to a depth of two to four inches with well- 
packed, clean, rather coarse sand, brickdust or pow- 
dered charcoal. Sometimes the whole bed is made of 
moss. These materials are used because they will not 
retain an excess of water if the proper provision is made 
for drainage. Sand is most used because it is as a rule 
readily obtained, but it needs to be selected with care, 
as it often contains injurious mineral matters. Sand 
found along the borders of fresh-water streams or lakes 
may generally be used without washing, but that dug 
from sandpits should in most cases be exposed to the air 
for a few weeks, and then be thoroughly washed before 
being employed for cuttings. The same sand should be 
used for but one lot of cuttings, as a rule, for it is liable 
to become infested with fungi that may work havoc 
with cuttings placed in it. 

369. Methods of Controlling Humidity. Where 
moisture needs to be controlled with especial care, as in 
propagating delicate plants from green cuttings, or in 
herbaceous grafting (393), the planted cuttings or the 



Propagation hy Cuttings. 



209 




grafted plants are often covered with bell- jars. To 
guard against sudden fluctuations in temperature, a 
larger bell- jar is sometimes placed over a smaller one. 
By means of a bell- jar with a tight- 
fitting ground plate, evaporation 
may be wholly prevented from cut- 
tings or plants, if do- 
sired. Propagating beds 
are often covered with 
glazed sash, in addition 
to the glass roof of the 
house, to assist in main- 
taining a moist atmos- 
phere about the cut- 
tings (Fig. 96). 
For convenience, we 
separate propagation by cuttings into two divisions, 
viz., propagation by cuttings from dormant and from 
active plants. The requirements of these two classes 
differ in some respects. 

a — Propagation hy cuttings from dormant plants. 

370. The Time to Make the Cuttings. We have 
seen that plant processes may not be wholly suspended 
during the dormant period (176). This is true not 
onl}'- of the plant as a whole, but also of detached parts 
of the plant, if they are protected from evaporation. 
If cuttings are taken from a plant in autumn and 
stored during winter in a moist place of moderate tem- 
perature, the cut surfaces will partially callus over 
(72), and the formation of roots or buds may com- 
mence before spring. 



Fig. 96. Propagating bed covered 
with glazed sash. 



210 Principles of Plant Culture. 

When new growing points must be developed before 
the cuttings can form a plant, as with cuttings of the 
stem and roots of many species, cuttings of dormant 
plants are preferably made at the beginning of the dor- 
mant period, i. e., in autumn, and placed during winter 
under conditions favoring the formation of new grow- 
ing points. 

371. The Storage of Cuttings. Cuttings should be 
stored in a place sufficiently moist to prevent loss of 
water by evaporation, and warm enough to favor mod- 
erate root growth. Cuttings with ready-formed buds 
must be kept cool enough to prevent growth of these. 
Root growth may proceed to some extent at tempera- 
tures too low to excite the buds. These conditions are 
usually fulfilled by covering the cuttings in damp saw- 
dust, sand or loose loam, and storing them through the 
winter in a moist, moderately ccol cellar, or by bury- 
ing them in the open ground beneath the frost line. In 
mild climates the latter plan is often preferable. Stem 
cuttings (373) of plants that do not root freely from 
the stem are frequently buried with the proximal end 
(115) uppermost. This gives them, to some extent, 
the advantage of bottom heat (362 a), since the sur- 
face layers of the soil are first warmed by the sun in 
spring. 

Cuttings stored in the ground over winter should be 
taken up and planted in spring before the buds expand. 

Cuttings of evergreen plants should not be buried, as 
this would destroy the leaves, without which they rarely 
form roots. Cuttings of these plants are usually made 
in autumn and planted at once in boxes of sand, which 



Propagation hy Cuttings. 



211 



are kept for a time in a light, cool place, as a cool 
greenhouse, until the growing points of the roots have 
formed, after which they are removed to a 
warmer location. 

372. Planting Cuttings in Autumn. Stem 

cuttings of the currant and other hardy plants, 

and root cuttings (376) of the blackberry, are 

sometimes made as soon as the wood is mature 

in autumn, and planted at once in well-drained 

loamy or sandy soil in the open ground. 

Cuttings thus treated often commence to 

form roots before winter. They should be 

covered with a little earth and mulched 

with some coarse litter on the approach of 

freezing weather, and should 

be shaded for a time after 

•the opening of spring (Fig. 

64). 

373. Cuttings from Dor- 
mant Stems (stem cuttings) 
usually form roots more 
promptly if the proximal 
end is cut off shortly below 
a node (115). (See Figs. 97, 
98 and 99). In certain 
plants, as many of the coni- 
FiG. 97. Fig. 98. Fig. 99. fers, cuttings rcot more 

Fig. 97. Stem cutting of cur- ^ 

rant. promptly when cut with a 

Fig. 98. Stem cutting of ^ . "^ 

grape. (Both after Bailey.) heel, 1. C., With a Small por- 

Fig. 99. Currant cutting . t p i 

rooted. tion 01 the wood 01 the pre- 

vious year at the base. The very short internodes at 




212 Principles of Plant Culture. 

the junction of the two season's growth appear to favor 
the emission of roots. Some varieties of the grape root 
more readily when a short section of the parent branch 
is removed with the cutting, forming a mallet- or 
T-shaped cutting {mallet cuttings). 

The cut forming the distal end of the cutting (115) 
is preferably made somewhat above a node, in order 
that the bud may not loose an undue amount of moist- 
ure by evaporation from the adjacent cut surface. 

Cuttings of certain plants that do not readily form 
roots when made in the ordinary way, may be induced 
to do so by "ringing" the branch from which the cut- 
ting is to be made (428 d), just below a node at about 
midsummer. Callus will then form at the upper edge 
of the ring (79), and food will be stored in the stem 
immediately above it. In autumn the branch may be 
severed just below the ring and a cutting made, of 
w^hich the base shall include the callused part, and 
which may be treated in the usual manner. 

374. The Proper Length for Stem Cuttings de- 
pends upon the conditions under which they are to be 
grown. Cuttings containing only one bud often root 
freely and form vigorous plants in the propagating 
bed, where heat and moisture may be readily controlled. 
Such short cuttings, however, are seldom used except 
when cutting wood is scarce. Cuttings intended for 
planting in the open ground are preferably made at 
least six inches long. 

375. How to Plant Stem Cuttings. The general 
rules given for the planting of seeds apply with nearly 
equal force to cuttings of the stem (344). Single-bud 



Propagation hy Cuttings. 213 

cuttings should be planted with the bud facing upward, 
and one-half to three-fourths inch deep, in order that 
the developing bud may readily reach the surface. Cut- 
tings of more than one bud may be placed upright or 
at an angle, at such a depth that the bud at the distal 
end (115) is about on a level with the surface. In cut- 
tings of shrubby plants desired to produce a single 
stem, the central buds should be rubbed off before 
planting, leaving but one or two buds at the distal end 
(Fig. 97). 

376. Propagation from Cuttings of the Root. Plants 
that naturally sucker from the root (347) and some 
others may be propagated from short pieces of the root 
{root cuttings). For this purpose roots of about the 
thickness of a lead-pencil are commonly cut into pieces 

one to three inches long 
(Fig. 100), as soon as growth 
ceases in autumn, and packed 
,„, „ , . ^ in boxes with alternate lav- 

FiG. 100. Root cutting of "^ 

blackberry. (After Bailey.) ers of moist Sand Or mCSS. 

The boxes are preferably stored in a cool cellar where 
they may be examined from time to time during win- 
ter; the sand or moss should be moistened when it ap- 
pears dry. Root cuttings of different varieties of the 
same plant often require different degrees of tempera- 
ture to induce the formation of callus and buds, hence 
the boxes should be frequently examined, particularly 
toward spring, in order that those in which the cut- 
tings are backward in starting may be placed in a 
higher temperature. Thus treated, root-cuttings of 
many hardy plants, as the plum, raspberry, blackberry, 




214 Principles of Plant Culture. 

jimeberry, etc., often form both buds and rootlets by 
spring, so that they may be planted directly in the 
open ground. Those of more tender species, as the 
bouvardia, geranium, etc., will not start to the same 
degree, unless placed in the propagating bed toward 
spring and given bottom heat. 

Root cuttings should be planted shallow, usually not 
more than one-half to three-fourths inch deep, in order 
that the developing bud may soon reach the light; oth- 
erwise, as in too-deeply planted seeds, the reserve food 
may be exhausted before the shoot reaches the surface. 
When planted in the open ground (372), the soil should 
be made very fine and carefully pressed about the cut- 
tings; if the weather is warm and dry, shading (Fig. 
64) and watering will be necessary. 

b — Propagation hy cuttings from active plants (green 
cuttings, slips). 

377. Nearly AH Plants may be Propagated from 
Green Cuttings. A succulent cutting of nasturtium* 
with its leaves intact, and with its proximal end im- 
mersed in fresh we^l- or spring-water, will for a time 
absorb sufficient of the liquid to make good the less 
from transpiration (74). So long as the water remains 
fresh and the tissues of the stem are unobstructed, 
the water thus al)sorbed will answer the same purpose 
to this cutting as if it had been absorbed by the roots. 
Food formation (58) will continue, and the growth 
current (79) will transport the prepared food from the 
leaves into the stem and in the direction of the roots. 
No roots being present, however, the growing points of 

* Tropceolum. 



Propagation by Cuttings. 215 

roots will form at the base of the stem, and we shall 
soon have a rooted cutting. Not all plants, however, 
root freely in water, possibly owing to an insufficient 
supply of oxygen therein. 

With very few exceptions, of which the greenhouse 
smilax* is one, cuttings of the succulent growi;h of the 
stem, with a certain amount of healthy leaf surface in- 
tact, will develop roots in all plants, under proper con- 
ditions of humidity and temperature ; hence propagation 
from green cuttings is a very common and expeditious 
method of multiplying plants. The healthy leaf sur- 
face, capable of preparing food, is a very important 
part of a green cutting, because the stem is less abun- 
dantly supplied with reserve food during the growth 
period than during the dormant period (184). 

Since the presence of leaf surface upon the cutting 
greatly promotes transpiration (74), propagation from 
green cuttings is scarcely practicable in the open air. 
Bottom heat (362), with a comparatively low air tem- 
perature, is especially important with green cuttings, in 
order that the food prepared in the leaves may be de- 
voted to the formation of roots. A small leaf surface 
on the cutting is generally preferable to a larger one ; 
in many plants, a portion of a single leaf is sufficient. 
The leaf surface should in no case be permitted to wilt, 
hence the cuttings should generally be sprinkled with 
water as soon as made. 

378. Especial Care is Necessary in Propagating 
plants from Green Cuttings. In planting the cuttings, 
the material of the propagating bed should be put in 

* Asparagus meteloides. 



216 



Frinciples of Plant Culture. 



close contact with the stems, and no leaves of the cut- 
tings should be covered. Since roots cannot form with- 
out oxygen, the bed must not be so freely watered as 
to exclude all air. Transpiration should be reduced by 
sheltering the cuttings from the direct rays of the sun. 
Movable screens used during sunshine only, are prefer- 
able to whitening the glass, which causes too much shade 
when the sun is not shining. 

Damping off, a much-dreaded disease causing cut- 
tings to ret at the surface of the bed, is promoted by 
excessive heat, over-watering, or insufficient 
light or air ; also by decomposing organic mat- 
ter in the material 



of the bed. Affected 
cuttings should be 
promptly removed 
and the trouble cor- 
rected. 

379. Green Cut- 
tings should be Pot- 
ted as Soon as Roots 
Form, which may be 





Fig. 101 

Fig. 101. 
mum. 

Fig. 102. 
eus 



Fig. 102. 
Cutting of chrysanthe- 

Rooted cutting of . col- 



(Both after Bailey.) 

detected by their foliage assuming a bright color. They 
should first be placed in small pots, and until they have 
commenced growth in these, should be treated pre- 
cisely as before they were potted. 

Propagation by green cuttings includes three divi- 
sions, of which the requirements differ in some respects, 
viz., propagation by cuttings of kerhaceous plants, of 
woody plants and of the leaf or parts of the leaf (leaf 
cuttings) . 



Propagation ty Cuttings. 217 

380. How to Make Green Cuttings of Herbaceous 

Plants. Ill herbaceous plants roots develop most read- 
ily from the younger and more succulent parts of the 
stem. Bend the shoot near its terminus in the form 
of a U, and then press the parts together. If the stem 
breaks with a snap, it is in the proper condition to 
root promptly; if it bends without breaking it has be- 
come too hard. Cutting below a node (115) is not es- 
sential to the formation of roots in herbaceous plants.* 
While the propagating house or hotbed is necessary 
to the extensive multiplication of herbaceous plants by 
green cuttings, the amateur may readily propagate a 
limited number of plants by the so-called "saucer sys- 
tem." The cuttings may be placed in glazed saucers 
containing sand that should be kept saturated with 
water. The saucers may be set in any warm, well- 
lighted place, as the window of a living room. The 
stems being in this case in contact with the water in 
the bottom of the saucer, the cuttings require less shad- 
ing than those in the propagating bed. 

381. How to Make Green Cuttings of Woody 
Plants. Cuttings of woody plants are preferably 
made of harder growths than those best suited to herba- 
ceous plants. They should be selected from young 
shoots of medium size and from half-mature wood, and 
should generally contain from two to three nodes, 
though where the material for cuttings is scarce, single 
buds may be used in many plants. The base of the 

* In a few plants, as the dahlia, the presence of a dormant 
bud at the crown is essential to the development of the stem the 
succeeding j-ear. Cuttings of such plants should therefore be 
made below a node, if the roots are desired for future use. 
15 



218 Principles of Plant Culture. 

cutting is preferably cut shortly below a node, but this 
is not essential in all plants. 

In this kind of propagation a mild bottom heat is 
helpful; though it is sometimes carried on during the 
summer months without artificial heat. 

382. Propagation by Leaf Cuttings. A considerable 
number of plants, including the bryophyllum, begonia, 
gesnera and others, readily develop growing points of 
the stem and roots upon their leaves, a fact often 
turned to account in propagating these plants. Well- 







r 

Fig. 103. Leaf of begonia on surface of propagating bed, form- 
ing young plants. (After Bailey.) 

matured leaves, with the principal nerves cut across on 
the under side, are held in close contact with the sur- 
face of the propagating bed by pegging or by light 
weights, or the leaf may be cut into pieces, which may 
be placed in the propagating bed and treated as ordi- 
nary green cuttings (378). 

The leaves of the bryophyllum form rootlets and 
buds from the notches on their borders wherever these 
chance to come in contact with a moist medium. 



Propagation hy Graf ting. 219 

h— Propagation hy grafting, 

383. Grafting consists in placing together two por- 
tions of a plant or of different plants, containing living 
cambium (68) in such a way that their cambium parts 
are maintained in intimate contact. If the operation 
is successful, growth will unite the two parts (69), 
and plant processes will go on much as if the parts 
had never been separated. The union usually takes 
place most rapidly when the cambium cells are in the 
state of most rapid division, i. e., when growth is most 
vigorous. 

The more intimate the contact of the cambium in the 
parts brought together, and the less injury their cells 
sustain in adjusting them, the more likely are they to 
unite. 

The plant that it is desired to change by grafting is 
called the stock, and the part designed to be united to 
the stock is called the cion (scion), graft or hud. 

Although the tissues of two plants of differing char- 
acter often unite in grafting, each of the united parts 
almost always retains its individual character. For ex- 
ample, if one or more buds of the Ben Davis apple are 
caused to unite by grafting with the stem of a Baldwin 
apple the parts that grow thereafter from the Ben 
Davis buds, though nourished by sap that has passed 
through the Baldwin roots and stem, with rare excep- 
tions, continue to be Ben Davis, while the parts that 
grow from the Baldwin stock continue to be Baldwin. 
To this fact is due the chief value of grafting, viz., it 
enables us to change the character of a plant. 



220 Principles of Plant Culture. 

384. Objects of Grafting. Grafting enables us 
a— To change a plant of an undesirable variety into 

one or more desirable ones; 

b — To preserve and multiply plants of varieties that 
cannot be preserved or multiplied by growing them 
from their seeds; 

c — To hasten the flowering or fruiting of seedlings 
grown with a view to improving varieties ; 

d— To change the size of trees, as to make them more 
dwarf ; 

e— To restore lost or defective branches; 

f— To adapt varieties to special soils; 

g— To save girdled trees; 

h— To avoid insect injury to the trunk or root, as in 
grafting the peach on the plum, cr the European grape 
on the American. 

385. The Plants that Unite by Grafting. Plants of 
different varieties of the same species (21) almost al- 
ways unite by grafting. Examples, the Ben Davis and 
Baldwin apples, the Bartlett and Seckel pears. 

Plants of different species of the same genus (21) 
often unite by grafting. Examples, the peach unites 
with the plum, many pears unite with the quince; the 
tomato unites with the potato. 

Plants of different genera in the same family or or- 
der (21) sometimes unite by grafting. Examples, the 
chestnut unites wath the oak; the pear unites with the 
thorn. 

Plants belonging to different families rarely unite 
by grafting. The oak and walnut and the fir and lin- 
den have been grafted. 



Propagation hy Grafting. 221 

The apparent resemblance of two plants of different 
species is not always evidence that they will nnite by 
grafting, e. g., the peach and apricot, though resem- 
bling each other in many respects, do not readily unite 
by grafting, but both unite freely when worked upon 
the plum, though the latter apparently differs from 
both the peach and apricot more than these differ from 
each other. 

Many plants unite freely when grafted in one direc- 
tion, that fail to unite when worked in the opposite 
direction; e. g., many cultivated cherries unite freely 
w^hen worked upon the mahaleb cherry, while the latter 
fails to unite when worked upon any of the cultivated 
cherries ; many pears unite freely when grafted upon 
the quince, but the quince dees not freely unite when 
worked upon the pear. The only sure way of deter- 
mining what species may be united by grafting is b}' 
trial. 

Three principal kinds of grafting are in use, viz., 
cion grafting, budding and approach grafting. 

386. Cion Grafting is used in grafting on roots 
(root-grafting) and very often in grafting on the stem, 
especially on large trees. The cion is a portion of the 
dormant stem, of the variety it is desired to propagate. 
It should generally be of the preceding season's growth 
and should always contain one cr more healthy leaf- 
buds* (131). It is probably best to cut cions from 
trees kno^^Ti to be fruitful. Cions are usually cut in 
autumn or during mild weather in winter or early 

* Flower-buds are occasionally used, but should be avoided -ex- 
cept in special cases. 



222 Principles of Plant Culture. 

spring, and are commonly stored, until needed for use, 
in a cool cellar packed in moist sawdust, moss or 
leaves. In climates of severe winters, they should al- 
ways be cut in autumn. Cions should not be kept so 
moist as to cause swelling of the buds or the forma- 
tion of callus (72), nor so dry as to cause shriveling. 

In cion grafting the proximal end of the cion (115) 
is joined to the distal end of the stock if the stock is a 
stem, or to the proximal end if it is a root in such a 
way that the cambium layers of the two coincide in at 
least one place. Cion grafting in the open air is usu- 
ally most successful when performed just before or 
during the resumption of active growth in spring, and 
the cion is thought to unite more readily if in a slightl^^ 
more dormant condition than the stock, possibly owing 
to its more ready absorption of water when in this 
state. 

The joints made in cion grafting are generally coated 
with a thin layer of. grafting-wax (387) or bound in 
grafting paper-, cloth- or cord (308, 309), to prevent 
evaporation and to keep out water. Sometimes the 
whole exposed part of the cion is waxed. 

387. To Make Grafting-Wax for cleft-grafting 
(392), melt together four parts, by weight, of un- 
bleached rosin, two parts of beeswax and one part of 
beef tallow; pour into water, and when sufficiently 
cool, work with the hands* until the mass assumes a 
buff color; make into rolls and wrap with parafined 
(waxed) paper to prevent the rolls from sticking to- 
gether. Several other formulas are in use. 

* The hands should be greased before touching the wax to pre- 
vent sticking-. 



Propagation hy Grafting. 



223 



For whip-grafting (390), where w^axed cord, cloth or 
paper is used, the beeswax may be omitted from the 
above formula, or one-half more tallow may be added. 




Fig. 104. Fig. 105. Fig. 106. 
Fig. 104. Grafting knife 



Fig. 107. Fig. 108. Fig. 109. Fig. 110. 
This should be of excellent steel. 
The curve in the blade is not essential. 

Fig. 105. Cion used for whip-, root- or cleft-grafting, one- 
fourth natural size. 

Fig. 106. Seedling root, used in root-grafting, one-fourth nat- 



ural size. 

Fig. 107. 
half. 

Fig. 108. 

Fig. 109. 

Fig. 110. 



Cion shaped ready for insertion, reduced nearly one- 
Portion of seedling root, shaped to receive the cion. 
The cion and portion of root, put together. 
The same as Fig. 109, wrapped with grafting paper. 



224 Principles of Plant Culture. 

388. Grafting Cord is made by soaking balls of com- 
mon wrapping twine in melted grafting-wax. 

389. Grafting Paper is made by painting thin ma- 
nilla paper with melted grafting-wax. For painting, 
the paper is preferably spread out on a board of the 
exact size of the sheet; to prevent too rapid cooling of 
the wax the board should be heated. The wax should 
be heated hot enough to spread easily, but not so hot 
that it is absorbed by the paper. Thin muslin or 
calico is often used instead of paper. 

Grafting paper and grafting cloth should be stored 
in a cool, moist place to preserve their adhesiveness. 

Many kinds of cion grafting slightly differing in de- 
tails have been described, but the more important are 
whip-grafting, cleft-grafting and side-grafting. 

390. In Whip-Grafting (splice-grafting, tongue, 
grafting) the cion and stock, are both cut off with a 
sloping cut, about an inch long, after which a tongue 
is formed on each by splitting the wood longitudinally 
a short distance (Figs. 107, 108). The cion is best cut 
behind a bud, as shown. 

In joining, the tongue of the cion is inserted into the 
split of the stock, so that the cambium line of the cion 
and stock (68) coincide on one edge, and the two are 
crowded together with considerable force, after which 
the joint is wrapped with a narrow strip of grafting 
paper or grafting cloth (389), or wound with grafting 
cord (388). Sometimes the joints are simply tied mth 
unwa*xed cord. 

Whip-grafting is generally used when the stock is 
little if any thicker than the cion. It is much used by 



Propagation hy Grafting. 225 

nurserymen in certain localities in grafting tlie apple 
and some other fruits upon roots (root-grafting (391)). 

Whip-grafting is also considerably used in some cli- 
mates of severe winters, in top-grafting or "top-work- 
ing" apple trees in the nursery, in order to give cer- 
tain slightly-tender varieties the benefit of a specially 
hardy stock. This grafting is performed on two or 
three-year-old trees, that have been grown from root 
grafts. The trunk is cut off at the height it is desired 
to form the head of the tree, and a cion of the variety 
to be propagated is inserted; or several cions are in- 
serted in as many branches. The latter method, while 
more expensive, has the advantage of giving to the 
top-grafted trees the branch formation of the stock, 
which is sometimes important. 

As growth starts on the top-grafted trees, shoots that 
push out from the stock should be rubbed off to pre- 
vent them from robbing the cions of nourishment. 

391. Root Grafting is generally performed in winter 
and in-doors. The stocks are small trees, grown one or 
two years from seed (seedlings). These are dug in au- 
tumn, and stored as recommended for cions (386). 
AVhen ready for grafting, the roots are washed and 
trimmed by cutting off the larger branch roots, after 
which the stem is cut off' at the crown, and the end of 
the root (115) is shaped as directed above (390). It 
is then cut off two or three inches down, and the re- 
maining root, if sufficiently thick, is shaped for another 
stock. Three or four stocks are sometimes made from 
a single root. As a rule, the stocks should not be less 
than three-sixteenths inch in diameter, nor less than 
two inches long. 



226 



Principles of Plant Cultnre. 



Some nurserymen prefer to make but a single stock 
from one root (''whole-root" grafts). 

Different nurserymen cut the cions for root-grafts 
from two to six inches long. In climates subject to 
drought in summer and severe freezing in winter, the 




Fig. 111. Shaping the cions for root-grafting. A, making the 
"long cut"; B, cutting the "tongue"; C, cutting off the cion. 
These positions, and the movements they indicate, are adapted to 
rapid work. 

longer cions are more satisfactory, as they permit the 
stock to be covered to a greater depth, and encourage 
rooting from the cion, which is sometimes regarded as 
an advantage. 

Root-grafts should be stored until time for planting 
out, as directed for cions (386). 

392. Cleft-Grafting is generally employed when the 
stock is considerably thicker than the cion. The cut-off 
end of the stock is split across its center, with a graft- 
ing chisel (Fig. 112), and the proximal end of the cion 
(115), which is cut wedge-shaped and a little thicker on 
one edge than the other, is so inserted into the cleft 
that the cambium of the thicker edge of the cion forms 
a line with the cambium of the stock (Figs, 113, 114, 
115). Success is promoted if the wedge-shaped por- 
tion of the cion contains a bud on its thicker edge. 
When the stock exceeds an inch in thickness, two cions 



Propagation hy Grafting. 



227 



are usually inserted (Fig. 114), to increase the chances 
of success. The elasticity of the stock should exert 
sufficient pressure to maintain very close contact be- 



tween it and the 
tightly bound 
The cions should 
yond the end of 
cut is usually 




cion; otherwise it should be 
with cord or raffia (393). 
contain at least one bud be- 
the stock. The wedge-shaped 
made about one inch long, 
and the cion should be in- 
serted into the cleft as far 
as the length of the 
wedge, after which all 
the exposed wounded 
surfaces, including 





Fig. 112. Grafting 
chisel for making 
the cleft in cleft- 
grafting. The point 
at the right is for 
holding the cleft 
open during inser- 
tion of cions. The 
projection above is 
for driving this 
point in or out; one- 
fifth natural size. 



Fig. 113. Fig. 114. 



Fig. 115. 



Fig. 113. Cion shaped ready for insertion 
in cleft. (After Bailey.) 

Fig. 114. Cions inserted in cleft, ready 
for waxing. 

Fig. 115. Cross-section of Fig. 113 (Af- 
ter Maynard). C, cambium layer of stock; 
C, cambium layer of cion. The cambium 
layers of the outer edge of the cion should 
form a continuous line with that of the 
stock. The cion is made a little thinner 
at its inner edge to permit the pressure of 
the stock to be exerted at the outer edge. 



the distal end of the cion, should be coated w^th graft- 
ing-wax (387). 

Cleft-grafting is most used in top-grafting old trees. 
Four to six of the main branches, located as nearly 



228 



Principles of Plant Culture. 




equidistant as possible (Fig. 116), are selected for 
grafting-, and it is desirable to graft these rather near 
to the top of the trunk. 

Branches exceeding two inches 
in diameter should not, as a rule, 
be grafted. About half of the 
top of the tree should be cut 
away just before the grafting, 
leaving some branches to utilize 
a part of the sap. The more or 
less horizontal branches should 

generally be selected for graft- ^^^ ,,g Branches of 
ing, and in these, the cleft should s'eYn ^from ^above^"lhow^- 
be made horizontally, to give the Sfns"^trmaki"r weli! 

J. • • , I 1 formed head. i. e., at the 

two cions inserted an equal op- dotted lines. 
portunity for growth. If both the cions in a branch 
grow, the weaker one should be pruned off later. As 

growth starts, shoots from the 
stock must be rubbed off 
(390). 

The spring following the 
top-grafting, all or a part of 
the branches left on the stock 
at grafting should be pruned 
Fig. 117. Cleft-graft in off to cncourage growth of the 

trunk of old grape vine. The _ , 

cions are usually inserted graits. It the tree IS large 

below the surface of the 

ground in grafting the grape, and of a vigOrOUS Variety, it 

and no wax is used. (After 

^^i^ey.) ig ^ige to leave a part of these 

branches until the second spring. 

393. Side-Grafting if chiefly practiced with plants 
in leaf, under glass. The cion is joined at the side of 




Propagation hy Grafting. 



09U 

LJiLl>J 



the stock, which is usually not cut off, and is secured 
in place by wrapping tightly with grafting cloth or 
raffia. Three slightly different methods are in use. 

a — A shaving of bark, thick enough to reach into the 
cambium layer, is removed from the side of the stock 
by making a long vertical cut and a short transverse 
cut at the base, and to this cut surface the cion is care- 
fully fitted, and bound with raffia. This method is called 
veneer-grafting . 

b — A sloping cut is made rather deeply into the sap- 
wood of the stock, into which the cion, after being ta- 
pered at its base to the form of a wedge, 
is inserted (Fig. 118), and the parts are 
then held closely together by binding with 
raffia. This method is generally employed 
in herbaceous grafting, as with the po- 
tato, tomato, etc. It is also much used in 
grafting evergreens under glass, and oc- 
casionally in grafting outdoor nursery 
trees. In the latter case, a coating of 
Fig. 118. Side- ^rafting wax is usually substituted for 

graft inserted, » » •^ 

ready for tying, the tying. 

c — A short, transverse incision is made, and imme- 
diately below this, a somewhat longer, vertical cut— 
the two cuts, w^hich are just deep enough to reach 
through the bark, forming a T (Fig. 121). The cion 
is then cut off with a long, sloping cut, and the point 
inserted, the cut surface inward, beneath the two lips 
of bark formed by the T-cut, after which the cion is 
crowded downward until its cut surface is in contact 
with the cambium layer of the stock, when the juncture 
is bound with raffia. 




230 Principles of Plant Culture. 

394. Budding is now extensively employed in propa- 
gating fruit trees, roses and the varieties of deciduous 
ornamental trees and shrubs. A (usually dormant) 
leaf-bud, with a small portion of surrounding 
bark (Fig. 120), is placed in contact with the 
cambium layer of the stock. Budding may be 
successful whenever the cells of the cambium 
layer are in a state of active 
division, as indicated by the 
ready separation of the 
bark from the wood. In 
climates having severe 
winters, budding is most 
satisfactory when per- 
for:i:ed near the end of 
the growing sea- 
son and with fully 
matured buds, in 
order that the 
buds may not ex- 
expand until the 
following spring ; 

Fig. 119. Fig. 121. Fig. 122. Fig. 120. tllUS the shoots 

Fig. 119. Shoot containing buds. The . „ , 

white spaces about the buds indicate the growing irom tlie 

amount of bark to be cut off with the bud. . , ^ ■, t -n 

The shoot is inverted for cutting the buds. in\Sertea DUd Will 

Fig. 120. Bud cut off. ready for insertion. 




Fig. 121. Bud partially inserted between 



and tied. (All 



have the whole 
season for growth 
and maturity. 
With plants that unite freely and with the stock in 
the proper condition, 



the lips of the stock. 

Fig. 122. Bud inserted 
after Bailey.) 



Propagation hy Grafting. 331 

395. Success in Budding Depends Upon 

a — A fresh condition of the huds; these must not be 
in the least shriveled from dryness. 

b — The proper removal and insertion of the hud; 
the growing point of the latter {Q>Q) must not be in- 
jured. If this comes out, leaving the bud-scales par- 
tially holloAV, the bud will not grow, even if properly 
inserted. The bud should be inserted promptly to 
avoid loss of moisture. 

c — The proper wrapping of the ivounded hark, to 
prevent evaporation and exclude moisture. The liga- 
ture should not cover the bud. 

d — The removal of the ligature after the union, to 
permit expansion of the stock. 

e — The cutting off of the stock just beyond the bud, 
when the latter commences growth, to stimulate its de- 
velopment. 

Two methods of budding are in use, viz., T- or shield- 
budding and ring- or annular-hudding . 

396. In T-Budding, which is the more common and 
expeditious method, a short shaving, containing a hard 
and plump bud, cut deep enough to reach through the 
cambium (Fig. 120), is inserted beneath the bark of 
the stock, as described for side-grafting (393 c). 

The buds, which should be plump and mature, and 
of the variety it is desired to propagate, are taken from 
shoots of the current season's growth. These shoots 
("bud sticks") (Fig. 119) should be cut the day the 
buds are to be inserted, and should be trimmed at once, 
and rolled in damp cloth, to prevent loss of moisture. 
The trimming consists in cutting off the leaves, saving a 



232 



Principles of Pla7it Culture. 



bit of the leaf stem to serve as a handle while inserting 
the buds. The stocks, whether grown from seeds or 
from cuttings, are usually of one or two season 's growth. 
The lower branches of the stock are cut off up to three 
inches or more from the ground, and a smooth place is 
selected for the bud, usually on the side least exposed 
to the sun's rays. With the budding knife, a T-shaped 
cut is made on the stock (393 c) about two inches above 




Fig. 123. A lesson in budding. The left-hand student is cut- 
ting a bud; the central one is lifting the lips of the bark with the 
spatula of his budding knife; the right-hand student is tying 
the bud. 



the ground. A bud is then cut from the bud stick, by 
inserting the blade of the budding-knife about a fourth 
of an inch below the bud, at such an angle that the 
back of the blade nearly touches the bark of the stick. 
The blade is passed just behind the bud, touching the 
wood, but not removing much of it, and then turned a 
little, running out about a fourth of an inch above the 
bud (Fig. 120). Often the knife does not run out, but 
the bark is cut off square, a quarter of an inch abovf 
the bud, as indicated in Fig. 119. 



Propagation by Grafting. 



233 



With the spatula of the budding knife (397), the lips 
of bark in the angles of the T-cut are loosened from the 
wood, when the bit of bark bearing the bud is slipped 
down behind them (Fig. 121), with the bud pointing 
upward, until the top end of tlie bit of bark is just 
below the horizontal cut of the T. Some budders do 
not use the spatula, but raise the lips of bark with the 
blade of the budding knife. The center of a strip of 
moistened raffia is then applied to the stock just below 
the inserted bud; the ends of the strip are crossed on 
the opposite side of the stock, brought forward and 
again crossed just above the bud, 
thus covering the horizontal cut of 
the T. The ends of the raffia are 
then brought behind the stock, tied 




Fig. 124. Fig. 125. Fig. 126. 

Fig. 124. Man budding in nursery row. (After Bailey.) 
Fig. 125. Budding- knife with ivory spatula on the end oppo- 
site the blade. 

Fig. 126. Budding knife made from erasing knife by rounding 
the edge at A. 

in a half knot, and drawn moderately tight (Fig. 122), 
pressing the lips down snugly about the bud, which 
now protrudes between the lips. 

If the bud "takes," it will unite with the stock in a 
few days. The raffia should be taken off in about ten 

16 



234 Principles of Plant Culture. 

days, by cutting it on the back side of the stock, to 
enable the latter to expand by growth. 

397. The Budding Knife should contain a blade of 
good steel, shaped as indicated in Fig. 125, and a 
round-edged spatula for lifting the bark. The spatula 
is better placed on the back of the blade, as shown in 
Fig. 126. 

398. Ring Budding is used to some extent in the 
propagation of thick-barked plants, as the hickory and 
magnolia. A section of bark is removed nearly or en- 
tirely around the stock, and a similar section contain- 
ing a bud from the variety it is desired to propagate, 
is fitted to its place and snugly bound with raffia. Ring 
budding is oftener performed in spring than later in 
the season. 

399. Approach Grafting is now seldom employed, 
except in a few plants that unite poorly by other meth- 
ods. It is only possible between two plants in close 
proximity, or between parts of the same plant, since 
the graft is not severed from the parent until it has 
united with the stock. The plants are nourished by 
their own roots until the union takes place. 

Approach grafting is performed during or just pre- 
vious to the growing season. The parts are held in 
contact by binding them with raffia; the juncture 
should also be waxed if the work is done in the open air. 
Two methods of approach grafting are in use: 
a — A shaving reaching into the cambium layer is re- 
moved from both stock and graft on the sides toward 
each other (Fig. 127), and the cut surfaces are brought 
together and closely bound until they unite (Fig. 128), 



Transplanting. 



235 



after which the graft is cut off below, and the stock 
above, the union. 

b — The top of the stock is cut oft' with a long sloping 
cut, preferably behind the bud, and the cut surface of 
the remaining part is inserted be- 
neath the bark of the graft, as de- 
scribed in side-grafting (393 c), ex- 
cept that the T-cut is inverted, and 
the stock is inserted from beneath. 



^^-M^' 




___ao^- 





FlG. 127. 



Fig. 128. 



Fig. 127. Two plants prepared for approach grafting. The cut 
surfaces, a a. are to be placed together and bound. 

Fig. 128. Two plants bound together for approach grafting. 
(After Bailey.) 

The graft is cut oft' below the point of union when 
the parts are fully united. 

In both these methods the graft should be severed 
gradually to avoid a check to the grow^th. 

Section II. Transplanting. 



400. Transplanting consists in lifting a plant from 
the medium in which its roots are established, and in 



236 Principles of Plant Culture. 

replanting the latter in a different location. Trans- 
planting is a violent operation because the younger 
roots with their root-hairs that absorb the greater part 
of the water required by the plant (101) are, as a rule, 
largely sacrificed in the lifting process. The water 
supply, so vitally important to the plant (62), is thus 
greatly curtailed until new root-hairs can be formed. 

Vigorous plants are generally better able to endure 
transplanting than feebler ones, because they can sooner 
repair the damage done to their roots. It follows that 
plants endure transplanting with less facility as they 
advance in age beyond the period of greatest vigor (9). 

401. The Most Favorable Time for Transplanting, 
in the case of plants that live more than one year, is 
during the dormant period, because growth processes 
are then least active, and comparatively little water is 
needed. In countries having mild winters, the most 
favorable time for transplanting is generally at the be- 
ginning of the dormant period, provided this comes at 
a moist season of the year. The roots will then have 
time to slowly callus over their wounds and to form 
new rootlets, and thus be prepared for active growth in 
spring. But in countries of severe winters, where the 
roots are largely frozen in the soil for two or three 
months, and in countries in which the autumn is gener- 
ally dry, spring is, as a rule, the more favorable season 
for transplanting. 

Trees that have been long exposed to cold, drying 
winds and have thus suffered depletion of water from 
their buds and branches, are better not lifted until the 
buds begin to swell. This is especially true of ever- 



Transplanting. 237 

green trees in severe climates. Being always in leaf 
these require more careful treatment than deciduous 
trees. 

"We shall consider transplanting under three divi- 
sions, viz., a, lifting the plant; h, removing the plant; 
and c, replanting the plant. 

A— LIFTING THE PLANT. 

402. The object to be obtained in this operation 
should be to remove the roots from the soil with the 
least possible damage consistent with reasonable econ- 
omy of time and labor. Plants in low vigor should 
receive especial care in this respect. Very young 
plants, as of tobacco, cabbage, lettuce, etc., grown 
thickly in the seed-bed, are often pulled from the soil 
with the hands. In this case, the soil of the bed should 
first be saturated with water, in crder that the roots 
may be broken as little as possible, and may come up 
with more or less adhering soil. It is generally prefer- 
able to grow such plants in drills rather than broad- 
cast. This enables them to be drawn from the soil with 
less damage to their roots. 

Trees and shrubs sufficiently grown for their final 
planting out should be more carefully handled. If it is 
necessary to cut off the main roots, the farther from 
the trunk this is done, the better for the tree, and the 
spade used should be kept as sharp as possible. The 
roots should not he harked, mangled or split hy the 
digging tools, as is so often done with nursery stock. 
Tree-digging machines are now much used by the 
larger nurserymen. 



238 Principles of Plant Culture. 

403. Lifting Large Trees. Trees considerably larger 
than nursery sizes are best lifted when the ground is 
frozen about their roots. A trench may be dug about 
the tree before the ground freezes, deep enough to per- 
mit the severing of the main roots, and a hole for the 
reception of the cylinder of earth left within the trench 
should also be dug at the place to which it is desired to 
remove the tree. This cylinder should be large enough 
so that the tree is left with abundant roots, or as large 
as can be removed with the apparatus at hand. When 
the ground is frozen to the proper depth, the tree may 
be tipped over by means of a rope and windlass, after 
which the cylinder of earth inclosing the roots may be 
pried up sufficiently to allow some low vehicle to be 
placed beneath it. The branches are usually permitted 
to drag upon the ground in removal, as the wounded 
parts may be cut off in the severe pruning necessary in 
planting large trees (409 c). 

Large trees may be lifted or lowered to accommodate 
grading. A trench is dug around the tree, leaving a 
cylinder of earth intact about the roots. Soil is then 
removed from beneath one side of the cylinder below 
the roots and a block set under as a fulcrum. The top 
of the tree is then inclined toward the fulcrum by 
means of a rope, until the roots are lifted on the op- 
posite side. If the tree is to be raised, soil is packed 
under the elevated roots, after which the top is tilted in 
the opposite direction, until the roots are lifted on the 
fulcrum side, when soil is placed under as before. This 
process is repeated until the tree has been lifted to the 



Transplanting. 



239 



desired height. If the tree is to be lowered, earth is 
removed at each tilt. 

404. Sacking the Earth-Enclosed Roots is practiced 
in lifting and removing orange trees in California and 
may be profitably employed with other evergreens. A 
rather deep trench is dng at one side of the tree, and 
from this trench, the deeper roots are severed. The 
top earth is then removed down to the first lateral 
roots, when all the remaining large roots are severed at 
some distance from the trunk. The tree is next tilted 
to one side and a piece of burlap or matting is drawn 
beneath it, after which the matting is folded about 
the earth cylinder and well tied. 



B— REMOVING THE PLANT. 

Plants with their roots out of the soil should be care- 
fully protected from mechanical injury, from drying 

and from freezing. To insure 
such protection, plants to be 
transported any considerable 
distance should be packed. 

405. Plants Packed for 
Transportation should be in- 
closed throughout, and the 
roots should be in close contact 
with some moist material, pref- 
erably bog moss. Straw^ is often 
used for this purpose and an- 
FiG. 129. Showing how swcrs wcll for packing about 

plants should be packed 

for shipping. the trunks and branches 01 

trees, but it is inferior to moss for inclosing roots, as 




240 Principles of Plant Culture. 

it is more liable to heat and does not so well retain 
moisture. 

Herbaceous plants, as the strawberry, cabbage, sweet 
potato, etc., may be packed in layers separated with 
moss, as follows : Over the bottom of a box, the width 
of which is about twice as long as the plants to be 
packed, and which has slatted sides, place a thin layer 
of damp (not wet) moss, and over this, place a layer 
formed of a double row of the plants, with their roots 
at the center, overlapping a little, and tops toward 
the sides of the box (Fig. 129). Then put in another 
layer of moss and so on until the box is full, or the 
desired quantity is packed. The thickness of the layers 
will depend upon the time of year, the temperature, 
the distance to be transported and the kind of plants. 
The warmer the weather, the thinner should be the lay- 
ers of plants, as a rule. When the top of the box is 
put on, the contents should be pressed sufficiently to 
prevent the plants from shaking out of place. 

406. Puddling the Roots of Trees, i. e., dipping 
them in a paste of soil and water, is much practiced by 
nurserymen and tends to prevent them from drying. 
The paste should be made with rather light, loamy 
soil and of the consistency of cream. 

407. Trees are commonly Bundled for Transporta- 
tion to economize space. For this purpose, a device 
resembling a sawbuck, with the arms cushioned with 
burlap or carpeting is very convenient. The trees are 
laid between the arms, with the roots placed evenly at 
one end. The stems are then drawn snugly together 
with a broad strap, after which they are bound with 



Transplanting. 



241 



soft cord or with young and tender shoots of the osier 
willow.* After bundling, the space between the roots 
should be filled with damp moss, and the whole mass o£ 
roots surrounded with the same material. If the dis- 
tance to be transported is short, the mossed roots may 
be sewed up in burlap or matting and the tops may be 
tied up in straight straw, or the whole bundle may be 
inclosed in burlap. If the distance is long, the bundle 
should be boxed, to more effectually prevent the tree 
from damage. The bundles may be packed very closely 
in the box without injury, provided they nowhere come 
in direct contact with it. Boxed or bundled trees, that 
cannot be shipped at once, should be stored in a cool, 
damp place. 

408. Unpacking and Heeling-In. Packed plants 
should generally be removed from their package as 
soon as they reach their destination. If they cannot be 
replanted immediately, they 
should be heeled-in. This con- 







FiG. 130. Nursery trees heeled-in to prevent drying. A, a 
short row of trees with only the roots covered. B, a row with 
their tops bent down and covered with earth at C. (After Green.) 
Sometimes the whole tops are covered. Trees should not be 
heeled-in in the bundles. 

sists in removing them from their bundles and tempo- 
rarily planting their roots in soil (Fig. 130). The 

*8alix viminalis. 



242 Principles of Plant Culture. 

roots should be well covered, and if at a dry season, 
they should also be mulched. To avoid mixing varie- 
ties, a separate row should be made of each sort. 

Nursery trees that cannot be packed for shipment at 
the proper time, are often lifted and heeled in, to 
retard the starting of the buds. 

C — REPLANTING. 

409. Preparation of the Plant, a — Washing the 
roots. The ''puddled" roots of nursery trees (406) 
are sometimes found inclosed at unpacking in a mass 
of mud that is so compact as to largely exclude the air 

(Fig. 131). The roots of such 
trees should be washed clean be- 
fore replanting (Fig. 132). 

b — Trimming the roots. The 

roots of trees that have been 

broken or mangled in the lifting 

or transportation should be cut 

Fig 131 Fig 132 ^^ck to souud wood witli a sharp 

Fig. 131. Puddled roots knife, 
of nursery tree. 

Fig. 132. The same Fibrous rooted plants, as the 

washed, ready for 

planting. strawberry, are much more read- 

ily planted when the roots are trimmed, as shown in 
Fig. 31. 

c — Reducing the top. The buds of trees and shrubs 
should generally be reduced in number at replanting 
to correspond with the destruction of the younger roots 
during the lifting process ; otherwise the water supplied 
by the roots may be insufficient to open the buds (62). 
This is best accomplished by thinning out and cutting 





Transplanting. 



243 



back the branches. As a rule, it is better to reduce the 
top rather sparingly at replanting, with the expecta- 
tion of cutting it back farther if the buds do not 
promptly open at the proper time. The branches that 





Fig. 133. Fig. 134. 

Fig. 133. Roots of tree properly planted. 
Fig. 134. Same improperly planted. 

can best be spared should be removed (420), Failure 
to properly reduce the top is a frequent cause of death 
or loss of vigor in transplanted trees. Small plants in 
leaf, as the strawberry, cabbage, etc., usually endure 
transplanting better if their larger leaves are removed 
at replanting. 

d — Wetting the roots just before replanting is quite 
important, as it favors intimate contact with the soil 
particles. 

Plants that have suffered from loss of moisture in 
transit should have their roots soaked in clean water for 
a few hours before replanting. Deciduous trees of 
which the bark is considerably shriveled may often be 
saved, if the center of the buds is still fresh, by burying 
th^m in moist earth until the bark resumes its plump- 
ness. 



244 



Principles of Plant Culture. 



410. Replanting the Roots. The object to be at- 
tained in this operation is to place moist and well-aer- 
ated soil in contact with all of the roots of the plant. 
The roots should also be placed at about the same 
depth, and in nearly the same position that they grew 
before the removal. 

Fig. 133 shows the roots of a tree properly planted. 
The hole was dug sufficiently large so that the roots 
were readily placed in it without crow^ding, and the 
soil was so well worked in among the roots that it 
comes in contact with their whole surface. 

Fig. 134 shows the roots of the same tree improperly 
planted. The hole was dug so small that the roots were 
necessarily crowded out of their nat- 
ural position, and the earth was 





Fig. 136. 



Fig. 137. 



Fig. 135. Strawberry plant too deeply planted. 
Fig. 136. The same planted too shallow. 
Fig. 137. Strawberry plant properly planted. 

thrown in so loosely that it comes in contact with only 
a part of the root surface. Distortion of the roots 
of trees and shrubs at planting may cause injurious 
root galls. 

In planting trees of which the roots are not already 
inclosed in soil (403), the hands should be freely used 
to brino^ the soil in contact with the w^hole root surface, 



Transplanting . 245 

and the earth should be moderately packed about the 
roots with the feet, or otherwise. 

If the soil is dry, it is probably better to moisten it 
before placing it about the roots, rather than after, as 
we have then a better opportunity 
to judge of the quantity of water 
required, and the soil is less likely 
to settle away from the roots. 

Trees of considerable size should 
generally be staked or otherwise 
supported after planting, to pro- 
vent shaking by wind (Fig. 138). 
Surrounding the trunk with poor- 
conducting material as hay, straw 
or canvas, tends to prevent dam- 
age from sun-scald (185), to which 
recently-transplanted trees 
are especially liable; as the 
evaporation stream (77) is 
much reduced, the bark 

tends to become unduly fig. 138. Large transplanted 
ViPQ+arl ^''^^ wound with hay rope and 

neaiCQ. supported by wires. 

411. Devices for Transplanting. With young trees 
and plants, that possess abundant vigor, rapidity of 
planting is often of greater importance than the ob- 
servance of precise rules. In this case, that method is 
best which secures a given number of transplanted and 
vigorously-growing plants at the least cost. The trans- 
planting devices shown in Figs. 139-141 aid greatly in 
accomplishing this end. 




246 



Principles of Plant Culture. 



The dihher (Fig. 139) is perhaps, aside from the 
spade, the most vahiab^e single tool for transplanting. 
It is used for opening the hole to receive the roots of 

small plants, as cab- 



^ 




bage, 




Fig. 139. 



Fig. 140. 



celery, onions, 
etc., and for 
pressing earth 
about the 
roots ; it an- 
swers equally 
well for plant- 
i n g cuttings 
a 11 d root 
grafts. The 
manner of us- 



FlG. 141. 
Flat steel dibber (one-sixth natural 
Tool for planting root grafts and ^^^ ^^ appears 



Fig. 139. 
size). 

Fig. 140. 
cuttings (much reduced). ,-q 

Fig. 141. Richards' transplanting tools, made 
by F. Richards, Freeport, N. Y. and 144 



Figs. 143 



Fig. 140 shows a very convenient tool for planting 
root grafts and cuttings. It consists of six steel dibbers, 
attached in a line to a piece of scantling, at the distance 
with a handle affixed above. In using this tool, the 
operator crowds the dibbers into the soil with the foot, 
guided by a line. He then moves the frame to and fro 
until the holes are sufficiently opened, when he with- 
draws the dibbers by lifting the frame, and pases on to 
repeat the operation. A person follows inserting the 
grafts or cuttings, and crowding earth about them with 
the ordinary dibber. 

Fig. 141 shows a set of transplanting tools, useful in 
removing a limited number of plants that are not 



Transplanting. 



247 



clcsely crowded and that need to be carried but a short 
distance. They are especially useful for transplanting 
strawberry plants during summer and autumn. These 

tools and also the Baldridge 
transplanter enable the plant 
to be readily lifted with a 
cylinder of earth and re- 
planted in a hole just large 
enough to receive the latter. 
Fig. 142 shows a success- 
ful machine for planting to- 
bacco, cabbage, strawberry 
and other low, herbaceous 
plants. It plants these as 

F,G. 142. Bern js^_^ Transplants- ^.^pj^jy ^^ ^^^.^ ^^^^ ^^^ ^^. 




er, made by 

Manufacturin, 

Wis. 



Co. 



Madison, ^-^^^ ^^^^^^ ^^ -^ -^ ^^^ proper 

position, and waters the soil about the roots at the same 
time. 

412. Potting and Shifting. Potting is the act of 
planting plants in greenhouse pots. 

The pots should be clean and are usually dipped in 
water before receiving the plants, until they have ab- 
sorbed as much of the liquid as they will take without 
leaving any upon the surface. Rooted cuttings are 
generally potted in pots one and one-half to two inches 
in diameter, and the plants are changed to larger pots 
{sliifted) as the roots require more room. Pots three 
inches or more in diameter are commonly filled one- 
third full or less with pieces of broken pots (potsherds) 
to insure abundant drainage, and these are often cov- 
ered with a little spagnum moss before putting in the 



248 



Principles of Pla7it Culture. 



soil. The soil used for potting should be of a sort that 
does not harden, "bake," on drying, and should gener- 
ally be liberally supplied with plant food. Decayed 
sods from an old pasture, leaf mold, decomposed ma- 
nure, and sand, the whole mixed and sifted through a 

coarse sieve, form a good potting 
soil. The proportions of the differ- 





Showing manner of using the dibber in planting. 

Fig. 143. Inserting roots in the hole opened by dibber. 

Fig. 144. Pressing earth about roots with the dibber. 

ent ingredients used vary with different plants. The 
soil should be moderately moist, and should be closely 
pressed about the roots. The details of potting are 
shown in Figs. 145 to 148. 

Shifting is the changing of a plant from one pot to 
another, usually a larger one. Plants in small pots are 
generally shifted as often as their roots begin to crowd, 
and the shifting is continued as long as further growth 
is expected. "When bloom is desired, the pots are per- 
mitted to become filled with roots (135). 



Transplanting. 



249 



The pots into which plants are to be shifted should 
be prepared as directed for potting. A little potting 
soil is placed in the bottom of the pot, or over the 





Fig. 145. Fig. 146. 

Fig. 145. The workman takes the pot in his left hand, and at 
the same time a handful of potting soil in the right hand. 

Fig. 146. He places the soil in the pot, pressing it against one 
side with the right hand, while he picks up a plant with the left 
hand. 

drainage material, after which the plant to be shifted 
is tipped out of its pot, by inverting the latter, placing 
the hand upon the surface of the soil, to support it, and 
tapping the rim of the pot gently upon the edge of the 
potting bench. 

If the soil is in proper condition, it will readily slip 
out of the pot intact, after which it should be placed in 
the center of the new pot and the space about it filled 
with potting soil moderately pressed down. The roots 
of woody plants should not be covered deeper than 
they grew before the shifting. See Figs. 150, 151 and 
152. 

17 



250 Principles of Plant Culture. 

D — AFTER-CARE OP TRANSPLANTED STOCK. 

413. Mulching the soil about transplanted plants 
(232) is very important in localities subject to drought. 
As a rule, it is wise to apply the mulch immediately 
after transplanting, but with trees transplanted very 




Fig. 147. 



Fig. 148. 



Fig. 147. Placing the roots of the plant against the soil in the 
pot with the left hand, he takes another handful of soil with the 
right hand. 

Fig. 148. He fills the remaining space in the pot with soil and 
presses it down with the thumbs, tapping the pot gently upon the 
bench in the meantime. 



early in spring, it is better to defer mulching until the 
soil becomes sufficiently warm to promote root absorp- 
tion (101). 

Watering recently-transplanted plants requires dis- 
cretion. As a rule, mulching is preferable to watering, 
but if mulching proves insufficient, watering is the last 



Transplanting. 251 

resort. In this case, the soil about the roots should be 
saturated with water and should not be permitted to 
become dry again until gro^\i;h starts. A hole may be 
made in the soil about the roots and kept filled with 
water until the liquid ceases to soak away rapidly, after 

which it should be occasionally filled 

until growth commences. 

414. Shading plants transplanted in 
leaf, until the roots resume activity, is 
important (235). Evergreen trees and 
shrubs may often be shaded with bar- 
rels or boxes, or with boughs from other 
evergreen trees. 

415. Tardy Starting into Growth 
after transplanting is usually evidence 
that the roots are not supplying suf- 
ficient water. In such cases, if other 
precautions have been observed, it is 
well to further reduce the top. Plants 
in this condition may sometimes be 
saved by wrapping the stem in oiled or 
rubber cloth to check loss of moisture, 

DevicrSr starting ^^' witli straw or moss which may be 
growth in trees. ^^.^^ frequently till growth starts. 

The device shown in Fig. 149 often causes recently 
planted trees to start growth that seem likely to fail 
without it. It consists of a flask or bottle containing 
distilled or rain water, supported a few feet above the 
ground and connected by a rubber tube with the cut-off 
end of a root, as shown. If the inverted flask is used, 




252 



Principles of Plant Culture. 



a short tube B B should extend through the cork and 
to near the bottom of the flask, to admit air. 




Fig. 150 Fiir. 151 Fig. 152 

Fig. 150. A poorly-potted plant. No provision is made for 

drainag-e; the pot is filled to the top with soil, leaving no space 
to receive the water; and tlie stem of the plant is not at the 
center of the pot. 

Fig. 151. A well-potted plant. A, potsherds; B, moss. 
Fig. 152. A poorly-shifted plant. C, open spaces due to in- 
sufficient pressing" of the soil. 

Flower-buds should generally be removed from re- 
cently-transplanted plants (139). 

Section III. Pruning. 

416. Pruning is the removal of a part of a plant, in 
order that the remainder may better serve our purpose. 

The parts of plants, being less highly specialized than 
those of animals, may be removed with less damage to 
the individual than is possible with animals, except in 
the lowest types. 

The word pruning, as commonly used, applies chiefly 
to the removal of parts of woody plants with the knife, 
shears or saw, but the operations defined below prop- 
erly come under the same head. 

a — Pinching is the removal with the thumb and fin- 
ger of the undeveloped nodes at the terminus of grow- 
ing shoots, in order to check growth. 



Pruning. 253 

b — Trimming or dressing, when applied to young 
nursery stcck, is the shortening of both roots and stem, 
preparatory to planting in nursery rows. The roots 
are shortened to facilitate planting, and the stems are 
shortened to reduce the number of buds (409 c). 

G— Topping is the removal of the flower stalk, as in 
tobacco, to prevent exhaustion of the plant by the for- 
mation of seed. 

d — De tasseling is the removal of the staminate flow- 
ers (tassels) of undesirable plants of Indian corn, to 
prevent pollination from them (150). 

e—Suckering is the removal of shoots that start about 
the base of the stem, or in the axils of the leaves, as 
in Indian corn or tobacco. Its object is to prevent ex- 
haustion of the plant by the production of needless 
shoots. 

f — Dishudding is the removal of dormant buds, to 
prevent the development of undesirable shoots. 

g — Ringing is the removal of a narrow belt of bark 
about a branch, to obstruct the current of prepared 
food (138). 

h— Notching is the cutting of a notch just above or 
below a bud or twig to modify its growth. 

i — Thinning fruit is the removal of a part of the 
fruits upon a plant, to permit the remaining ones to 
attain larger size, and to prevent exhaustion of the 
plant by excessive seed production. 

2~ Deflowering or definiting is the removal of flower- 
buds or fruits to prevent exhaustion of the plant (139). 

k — Boot pruning is the shortening of the roots of 
plants in the soil, to check growth, or to stimulate the 
formation of branch roots nearer the trunk (104). 



254 Principles of Plant Culture. 

I— Sprouting is the removal of sterile shoots or water 
sprouts from the upper part of the grape vine. 

417. The Season for Pruning. The milder kinds of 
pruning, as pinching and disbudding, may be per- 
formed whenever the necessity for them appears. But 
in perennial plants, severe pruning, as the removal of 
branches of considerable size, is generally least inju- 
rious if performed during the dormant period. As the 
exposure of unhealed wounds may cause damage from 
drying, and invites infection by injurious fungi (320), 
severe pruning is commonly best performed toward the 
end of the dormant period, i. e., in early spring be- 
cause healing is most rapid at the beginning of the 
growing season (72). Pruning should not, however, 
be done at a time when sap flows freely from wounds, 
as this tends to waste reserve food. In plants subject 
to this, as the maples and grape, pruning is probably 
best performed just before or just after the sap-flowing 
period. 

418. Where and How should the Cut be Made in 
Pruning? Since the movement of prepared food is 
mainly from the leaves toward the root (80), it follows 
that when a branch is cut off at some distance from the 
member that supports it, the wound usually will not 
heal, unless there are leaves beyond the wound to man- 
ufacture food, and thus make a growth current possi- 
ble (72). The cut should, therefore, be made close 
enough to the supporting member so that it can be 
healed from the cambium of the latter. In woody 
plants, there is usually a more or less distinct swelling 
about the base of a branch (Fig. 153), produced by the 



Pruning. 



255 



cambium of the supporting member and just beyond 
this swelling, a more or less distinct line marks the 
point where the cambium of the branch and of the sup- 
porting members unite. In a healthy tree, a wound 
made by a branch of reasonable size, cut off at this 




Fig. 153. 



Fig. 154. 



Fig. 155. 



Fig. 153. Showing tfie proper place to make the cut in prun- 
ing. A wound made by a cut on the dotted line A-B will be 
promptly healed. One made on the line C-D or E-F will not. 
In Fig. 154 the lower branch was cut off too far from the trunk. 

Fig. 154. Showing how to make the cut in pruning large 
branches. The upper cut, all made from above, permits the branch 
to split down. The left cut, first made partly from below, pre- 
vents splitting down. 

Fig. 155. Pruning to an outside or inside bud. Cut as in the 
figure, the uppermost bud would form a shoot that tends to ver- 
tical. Cut on the dotted line, the uppermost bud would form a 
shoot tending to horizontal. 

line, will usually heal promptly, but if the cut is made 
much farther out, it will not. 

The cut should generally be made at right angles 
with the branch, rather than parallel to the supporting 
member, since it is important that the wound be jio 
larger than is necessary. Wounds so large that they 
cannot heal promptly should be painted with lead and 
oil paint to preserve the wood. 

419. Unhealed Wounds Introduce Decay into the 
heartwood of trees. Since the cells of the heartwood 



256 Principles of Flant Culture. 

form a congenial field for certain destructive fungi 
(321), that having oilce gained entrance, sooner or 
later destroy the heartwood of the whole trunk, thus 
greatly weakening it and preparing the way for the 
final destruction of the tree. 

420. Objects of Pruning. If intelligently performed, 
pruning has one of four objects in view, viz. : 

a — To change the form of the plant, as to outline or 
density {foymiative pruning). 

b — To stinuilate development in some special part, as 
to promote the growth of wood or the formation of 
flower-buds (stimulative pruning.) 

c — To prevent some impending evil to the plant, as 
to arrest or exclude disease (protective pruning). 

d—To hasten or retard maturity (maturative prun- 
ing). 

A— FORMATIVE PRUNING. 

This aims to regulate the form of the plant with 
reference to outline or density, or to strength of stem. 
Pruning for outline includes pruning (a) for symmetry 
or picturesqueness ; (b) for stocUiness or slenderness. 

421. Pruning for Symmetry aims to develop in the 
plant a head that is symmetric with reference to its 
trunk. The general principle involved is the suppres- 
sion of growth in all parts that tend to grow beyond 
the lines of symmetry (Fig. 156). This is bes-t accom- 
plished by pinching (416 a) during the growth period, 
thus economizing the plant's energy; but when the 
pinching has been neglected, the shoots that grew out 



Pruning. 



257 



of symmetry may be cut back during the dormant 
period. 

In pruning for symmetry, the plant should generally 
be encouraged to develop the form that is natural to 
the particular species or variety, e. g., the American 
elm tree,* which naturally develops an open, some- 




FiG. 156. Pruning for symmetry. The branches growing be- 
yond the ideal outline, indicated by the dotted line, should be cut 
off at the points indicated. 

what spreading head, tending to be broadest toward 
the top, should not be pruned to the same form as the 
sugar maplef that develops a more roundish and com- 
pact head. Evergreens are sometimes pruned to ideal 
forms, as in topiary work, a practice that is generally 
condemned by good taste. 



* Ulmus Americana. 



f Acer saccharinuni. 



258 



Principles of Plant Culture. 



422. Pruning for Picturesqueness is seldom em- 
ployed. It requires a thorough knowledge of pruning 
and of plant growth, combined with the conceptions of 
the artist. 

423. Pruning for Stockiness aims to develop a low 

head, with abundant 
branching, and a strong 
trunk. It is best accom- 
plished by pinching 
(416 a) the uppermost 
growing points during 
the growth period, and 
encouraging low branch- 
ing on the stem. If a 




Fig. 157. Raspberry cane 
rendered stocky by prun- 
ing. 




Fig. 158. Raspberry 
cane not pruned. 



spreading form is de- 
sired, the lower branches 
should be pruned to outside buds (Fig. 155). 

Pruning for stockiness is much practiced in the 
raspberry (Figs. 157 and 158) and blackberry, 
in hedges and in many ornamental plants. It 
tends to the production of flower-buds, by check- 
ing growth of wood (136). 

424. Pruning for Slenderness is seldom neces- 
sary, as a slender growth may readily be produced 
close planting. It is accomplished by persistently 



by 



re- 



Pruning. 



259 




moving or cutting back the lower branches, and per- 
mitting only a few branches to develop near the ter- 
minus of the stem. ^ 

425. Pruning for Den- 
sity applies either to in- 
creasing or decreasing the 
density of the head. In 
ornamental and shade 

trees, a compact head is fig. 159. Showing how to disbud 

shoots of some coniferous trees. 

often desirable, while in Picking out the terminal bud A 

' in spring usually causes both the 

fruit trees, a head that adjacent lateral buds to develop. 

admits abundant light and air (Fig. 162) is important 
(242). To increase density, encourage lateral branch- 
ing by pinching 
all the more 
prominent ter- 
minal growing 
points (Fig. 
160). In some 
coniferous trees, 
as the Norway 
spruce,* disbud- 
ding of the terminal shoots 
(Fig. 159) in spring is advis- 
able, and in woody plants too 
Fig. 160. Showing how den- tall for pinching, the more 

sity of growth is promoted 

(right-hand side) by persist- prominent terminal growing 

ent pinching of the terminal 

growing points. points may be cut back with 

the pole shears (431), which causes the head to grow^ 
more dense. 




* Picea excelsa. 



260 



Principles of Plant Culture. 



In pruning to form an open head (Fig. 162), it is 
wiser, as a rule, to thin out the smaller branches at 
some distance from the trunk than to remove large 
branches at their union with the trunk. The clearer 
the atmosphere in a given locality, the less thinning 
of the top is required to produce the maximum number 
of fruit buds (243). 






-r_-\ 







'■^ ' »■ "^is'''' ""r 




Fig. 161. Unpruned apple tree, with head too dense to admit 
light. 



426. Pruning for Strength, a— 0/ the Trunk. Trees 
and plants grown in closely-planted nursery rows often 
have trunks insufficiently developed to support the 
head, when planted by themselves. To remedy this de- 
fect, we promote the formation of new vascular bun- 



Pruning. 



261 



dies (67, 123) by inducing branching, which we ac- 
complish by cutting back the top in proportion to tlie 
slenderness of the trunk (423). 

h—of the Branches. Trees expected to support heavy 
crops of fruit, or to endure high winds, should have 




Fig. 162. Apple tree pruned with open head, to admit abun- 
dant light. 



branches developed with special reference to strength. 
In such cases, several medium to small branches are 
better able to endure the strain than a few large ones 



262 



Principles of Plant Culture. 



(245 b), and the loss to the tree of a small branch, 
should it occur, is less serious than that of a large one. 
Forming the head of fruit trees of three or four main 
branches is to be discouraged for this reason. Several 
small branches from a common trunk are better, and 
these should be encouraged to leave the trunk at nearly 
right angles -(Fig. 155). Forks in the trunk of fruit 
trees, dividing the wood into two nearly equal parts 
are objectionable, as one or the other part is very liable 
to split down under the weight of a heavy fruit crop. 

Main branches inclined to split down may sometimes 
be prevented from doing so, by twisting two smaller 
branches together, to form a connection between them 

(Fig. 163). The branches thus 
twisted often grow together, form- 
ing a tie of great strength. A main 
branch that has actually com- 
menced to split down may often 
be saved by passing an iron bolt 
through it and the remainder of 
the trunk. A bolt tlius inserted 
may become entirely inclosed by 
later growth. 

B— STIMULATIVE PRUNING. 

o/f?uir tree "^tSd^ to- ' "^^^^ depends upon the principle 
gether by a graft that the suppression of growth in 




formed 
twigs. 



of twisted 



one direction tends to sti7nidate it 
in others. Stimulative pruning may be employed either 
to stimulate growth of leaves, branches and roots, or 
of flower-buds. 



Pnimng. 263 

427. a— Pruning for Growth may be performed, (a) 
By removing a part of the hranclies, thus reducing the 
number of growing points and the surface exposed to 
evaporation. Plants that are not making satisfactory 
growth through feeble root action, may often be in- 
vigorated by this treatment, which is especially useful 
in trees recently transplanted or weakened by over- 
bearing. 

(b) By suppressing reproduction. When growth is 
desired, it is often advisable to prevent the develop- 
ment of flowers. Newly planted strawberry, raspberry 
and blackberry plants usually make better growth the 
first season if the flower-buds are picked off. The re- 
moval of flowers in the potato plant tends to stimulate 
the growth of tubers, especially in varieties that form 
seed. The removal of flower-buds from cuttings in the 
propagating bed encourages the formation of roots. 
Topping tobacco and rhubarb plants (416 c) causes 
the leaves to grow larger, and of onion plants stimu- 
lates growth of the bulbs. De-tasseling corn encourages 
growth of the ears (416 d). Thinning fruit on plants 
that incline to overbear, causes the remaining fruits 
to grow larger (416 i, 159). 

428. b— Pruning for Flowers or Fruit. Since check- 
ing growth tends to stimulate the formation of flower- 
buds (134 b), we encourage flowering in plants that in- 
cline to luxuriant growth, by pruning which tends to 
check vigor. This may be accomplished, 

(a) By pinching the terminal buds during the 
grow^th period^ as is often practiced upon tardy-bearing 
fruit trees or upon seedling fruit trees of which it is 



264 Principles of Plant Culture. 

desirable to soon learn the quality of the fruit. To be 
successful, it must be performed rather early in the 
growing season, and before the time for the formation 
of flower-buds. The blossoms do not usually appear 
until the season following the pinching. 

With plants that flower at the terminal growing 
points of the principal branches, as the spiraeas, hy- 
drangeas, rhododendrons, etc., pinching to promote 
flowering is not advisable, as it tends to reduce the 
size of the flower clusters. 

(b) By cutting hack the new growth. Woody plants 
that flower on stems more than one year old, as the 
apple, pear, currant, etc., when grown on rich or well 
cultivated ground, or that have been too severely 
pruned, often tend to produce an excess of new wood 
with a very feeble development of flower-buds. In 
such cases, it is advisable to equalize the growth by a 
moderate cutting back of all the young shoots. This 
must, however, be done with judgment. If the cut- 
ting back is too severe, it will stimulate more wood 
growth rather than the development of flower-buds. 

(c) By root pruning. This checks growth by reduc- 
ing the number of root-tips, and thus cuts off a part of 
the water supply. It is applicable to the same cases as 
pinching, and is accomplished by cutting off the ex- 
tremities of the roots by inserting the spade in a circle 
about the plant, or in the case of trees of considerable 
size, by digging a trench sufficiently deep to sever the 
lateral roots. The severity of the root pruning advis- 
able will depend upon the vigor of the growth it is de- 
sired to check. 



Pruning. 265 

(d) By obstructing the groivth current. This is ac- 
complished by ringing (416 g), by notching (416 h) 
and by peeling the stem (72). 

When ringing is practiced, the width of the belt of 
bark removed should usually not be so great that the 
wound cannot heal over the same season by the callus 
formed on the upper edge of the ring (79), and it must 
be made sufficiently early to give time for healing. A 
wider ring will sometimes heal if the ringing tools are 
not inserted deeper than the cambium layer (80). In 
the grape vine, in which ringing is often practiced to 
increase the size and earliness of the fruit, the width 
of the belt removed is less important, since the canes 
that have borne fruit are generally removed in the 
annual pruning. But in fruit trees, the belt of bark 
removed should not much exceed one-eighth inch in 
width. Simply cutting through the bark with the 
pruning saw often accomplishes the desired end. 

Notching above or below a bud or twig affects it much 
as ringing affects the entire ringed member. Notching 
below a bud or twig, therefore, checks its growth, and 
is often followed by fruiting in that part. 

Peeling the stem has sometimes been practiced to 
make barren trees fruitful (72). It is a hazardous 
operation at best, and should only be used as a last 
resort. It is accomplished by making two cuts around 
the trunk, usually several inches apart, and just 
through the bark, with one or more vertical cuts be- 
tween them, after which the bark between the circular 
cuts is carefully peeled off. It should only be per- 
formed during a period of very rapid growth, and at 

18 



266 Principles of Plant Culture. 

a time when the wood is well supplied with reserve 
food, i. e., some time after the tree has put out leaves. 
It is most likely to succeed in warm, dry weather, and 
when the wound is not shaded after peeling; otherwise, 
injurious fungi are apt to infect the ruptured cells. 

C— PROTECTIVE PRUNING. 

429. Dead or Dying Members of a plant Should Be 
Promptly Removed, since they more or less endanger 
its well-being. Dead branches of any considerable size 
invite decay into the stem which often results disas- 
trously (419). Branches that are dying from infection 
by a fungous parasite, as the apple or pear blight, or 
the black knot of the plum (323), are especially dan- 
gerous and should always be removed as soon as dis- 
covered. Branches that tend to interfere with the 
groT\i:h of others already formed should be checked by 
pinching (416 a), and those that interfere by too close 
contact should be cut back in proportion to the inter- 
ference. 

Scraping off the dead bark scales from old fruit trees 
tends to remove certain destructive insects or their 
eggs. It should be done during the growing season, 
and a short-handled hoe or a box-scraper is convenient 
for the work. Trees subject to sun-scald should gener- 
ally not be scraped unless other trunk protection is 
given. 

D— MATURATIVE PRUNING. 

430. R— Pruning to hasten maturity. This is seldom 
practiced. In nursery trees that tend to grow too late, 
and are thus subject to winter killing, the leaves are 



Pruning. 



267 



sometimes removed two or three weeks before the time 
when hard frosts are expected, to encourage ripening 
of the wood. 

The later tobacco plants in a plantation are usually 
topped at the time the main crop is pushing the flower 
stalk, which causes their leaves to mature in season to 
be harvested with the rest of the crop. 

h— Pruning to retard maturity, see (158). 

431. The Principal Pruning Implements are the 
following : 

The pruning knife. (Fig. 164) is useful for removing 
small woody shoots. The blade should be of good steel, 
==3 ^\,^^,y) ^^^ t^^ point should curve forward 
/ )*'-^^\ a little, to prevent the edge from 





Fig. 164. Fig. 165. Fig. 166. 

Fig. 164. Pruning knife. Fig. 165 
Fig. 166. Pruning shears. Fig. 167 



Fig. 167. 

Pruning saw. 

Hedge shears (much reduced). 



slipping off the branch. The handle should be large to 
avoid blistering the hand, the base of the blade should 
be thick to furnish support for the thumb, and the rivet 



268 



Principles of Pla7it Culture. 





should be strong enongli to sustain hard pressure upon 
the handle. 

In using the pruning knife, the shoot to be cut off 
should generally be pressed with one hand toward the 
member that supports it and the blade should be in- 
serted at the proximal side. Care is necessary to pre- 
vent the blade from cutting too far. 

The priming saw (Fig. 165) is useful for cutting off 
large limbs. Two toothed edges are preferable to one, 
as the second edge tends to prevent ''pinch- 
ing." It is well to have the teeth on one edge 
point backward, as this enables the saw to cut 
either when pushed or pulled. Sometimes the 
blade is curved 
like a sabre, with 
the teeth on the 
concave edge 
pointing back- 
ward. The blade 
should taper near- 
ly to a point, to 
enable it to enter 
between crowded 
branches. 

The p r n n i n g 
shears (Fig. 166) 
may be used for 
the same purpose 
as the pruning knife, but they cut less smoothly, and 
less close to the supporting member. They should be 
used with the beveled edge of the blade in close contact 



Fig. 168. Fig. 169. Fig. 170. 

Fig. 168. Lever shears (much reduced). 
Fig. 169. Pole shears. The wire con- 
nects with a lever not shown in the figure. 
Fig. 170. Raspberry hook. 



Pruning. 269 

\^dth the supporting member. They are excellent for 
cutting cions (386), and making cuttings (358). The 
form shown in the figure is perhaps the best one extant. 

The hedge shears (Fig. 167) are especially useful for 
pruning hedges. 

The lever shears (Fig. 168) are useful for cutting 
off sprouts about the base of trees. 

The pole shears (Fig. 169) are useful for cutting 
back the shoots of tall trees, and for removing sap 
sprouts (223), though for this purpose they have the 
fault of the pruning shears in not cutting sufficiently 
close to the branch. They should not be used for shoots 
much exceeding one-half inch in diameter. 

The raspberry hook (Fig. 170) is used for cutting 
off the dead fruiting canes of the raspberry and black- 
berry. The cutting part is made of a rod of good steel, 
five-sixteenths inch in diameter, flattened and curved as 
shown, with a moderately thin edge on the concave 
side of the curve. The handle should be about three 
feet long. 



The following books are recommended for reading in 
connection with the preceding chapter: The Nursery 
Book, Bailey; Greenhouse Construction, Taft; Barry's 
Fruit Garden, Barry ; The Art of Grafting, Baltet ; The 
Pruning Book, Bailey; How to Make the Garden Pay, 
Greiner. 



CHAPTER V. 
PLANT BREEDING. 

432. Plants Have Improved Under Culture. From 
our point of view, our cultivated varieties of plants are 
superior to their wild prototypes. The strawberries of 
our gardens are larger, more productive and firmer 
than those of the fields; the cultivated lettuces are 
more vigorous, more tender and milder in flavor than 
wild lettuces; and the cultivated cabbages and cauli- 
flower are greatly superior, in the food products they 
furnish, to their progenitor. The superior qualities of 
long-cultivated plants, as compared with their wild 
parents, is conspicuous whenever the wild form is 
known. 

433. Whence this Improvement? It probably re- 
sults from two causes, a— In culture, the natural hin- 
drances to development are largely removed. Culti- 
vated plants are less crowded by too-near neighbors 
than wild plants, and they commonly receive more 
abundant food and moisture. They are, therefore, able 
to reach higher stages of development than is possible 
in nature, where plants are constantly restricted by 
environment. 

b — The principle of selection has doubtless been more 
or less operative since the beginning of culture (19). 
All of our cultivated plants must have existed origi- 
nally in the wild state. The most satisfactory plants 
of any desirable species have been most carefully 



Plant Breeding. 271 

guarded, and when the art of propagation became 
known, these plants were most multiplied. In each 
successive generation, the most desirable individual 
plants of each species were protected and multiplied, 
or at least were permitted to perpetuate themselves. 
Since the offspring tends to resemble the parent (18), 
the persistent propagation from the best has resulted 
in more or less marked improvement. Chance cross- 
ings have aided the process (445). These facts fur- 
nish hints for the further improvement of plants. 

434. The Variability of plants Renders their Im- 
provement Possible. In a species of which the indi- 
vidual plants are ail practically alike, as in many wild 
plants, we can do little in the way of plant breeding, 
except to give treatment that promotes variability. In 
a species in which the individuals manifest different 
qualities, however, we may hope to secure improvement 
by using the more desirable plants as parents from 
which to secure still further variability. 

435. Variations are Not Always Permanent. If we 
find a chance seedling of the wild blackberry, for ex- 
ample, that has remarkably fine fruit, the plants 
grown from seeds of this fruit are not always equal in 
quality to the parent. The tendency, in such cases, is 
for the seedling plants to revert or go back to the ordi- 
nary type of the species, and the more marked the 
variation, the stronger is the tendency to reversion. 

436. How to Fix Desirable Variations. A fixed 
variation, i. e., a variation of which the progeny re- 
sembles the parent in all important characters, be- 



272 Principles of Plant Culture. 

comes a variety (21)*^as this word is used with refer- 
ence to cultivated plants. There are two possible ways 
of fixing a desirable variation: 

a — By propagating the plant hy division (345). This 
enables us to maintain a given variation through manj" 
generations with comparatively little deviation from 
the form w^ith which we started (341). Our varieties 
of fruits; potatoes, geraniums and many flowering plants, 
and of many of our finest ornamental trees and shrubs 
are fixed in this manner. It is well known that varie- 
ties propagated in this way rarely "come true" from 
seed, i. e., their seed does not usually produce plants of 
the same variety as the parent. Bi-it it is not practi- 
cable to propagate all plants by division. 

With plants more conveniently propagated from seed, 
as the cereals, Indian corn and most garden vegetables, 
we may fix varieties to a certain limit. 

h—By persistent selection towurd an ideal type. For 
example, if we discover a single pea plant in a row of 
peas that produces earlier pods than any other plant 
and we desire to fix this variation, we would save all 
the peas from this plant and sow them the next spring. 
Most of the plants from this seed will probably be later 
than the parent, but two or three of them may equal 
it in earliness. We would save the seeds from the 
earliest plant again, and continue this selection througli 
several seasons. It would be well to note the incidental 
characters of the earliest plants, i. e., whether the pods 
are borne singly or in pairs, if they are straight or 



* Varieties that produce their more important chai'acters when 
grown from seed, are often called races. 



Plant Breeding. 273 

crooked, and whether the plants are tall or dwarf. Hav- 
ing decided on the characters that seem to accompany 
the extreme earliness, we should save seeds only from 
plants that show all these characters. After following 
this kind of selection eight or ten years, we may be 
able to introduce a ncAV variety of pea. 

It is impossible to so fix variations in plants grown 
from seed that they wdll continue to come true without 
a certain amount of selection, hence varieties propa- 
gated by seed continually tend to ''run out," i. e., to 
lose their distinctive characters. Seed growers find it 
necessary to use the utmost care in maintaining their 
varieties, and the more distinct a variety propagated 
by seed, the more difficult it is to maintain. 

437. Seed Selection is of Great Importance. From 
what has been said, it is clear that the cultivator can- 
not afford to be indifferent as to the quality of the 
seed he sows. It is not enough that the seed is fresh 
and plump ; it should be of carefully-bred varieties. In 
the cabbage and cauliflower, success or failure in the 
crop will depend largely upon the quality of seed sown, 
and the same is more or less true in all crops grown 
from seed. 

438. We Can Induce Variation, in some cases, by 
special treatment of the parent plants, or by the use of 
a particular selection of seed. 

R—By culture. It is generally conceded that culture 
tends to promote variations that would not have ap- 
peared in the wild state, in consequence of the changed 
growth conditions. In improving wild plants, there- 
fore, we probably have a better chance of securing 



274 Principles of Plant Culture. 

variation by gathering seeds from such wild plants that 
have been placed under high cultivation than from 
those that have not been submitted to culture. 

h—By growing seedlings. In plants habitually pro- 
pagated by division (345), as the apple, potato, dahlia, 
etc., we secure variation by growing plants from seed. 
The parent plant, not having been fixed by long selec- 
tion, as is the case with varieties grown from seed, is 
in a state of variation, and hence its progeny usually 
varies widely. From these variable seedlings, desirable 
individuals may be selected for fixing. Since most of 
our varieties that are propagated by division are highly 
developed, their seedlings are usuaUy, though not nec- 
essarily, inferior to the parents. 

c — By crossing varieties or species. This is the most 
important method of plant improvement. By procur- 
ing fecundation of the germ cell of a plant of one vari- 
ety with pollen from a plant of a different variety or 
species (149) through cross-pollination (151), we ob- 
tain a variable progeny of which the individual plants 
may be expected to resemble both jiarents in different 
degrees. For example, if we secure fecundation of a 
number of ovules of the Worden grape with pollen 
from the Delaware grape, and plant the seeds from the 
fruits thus secured, we may expect that some of the 
seedlings will resemble both parents about equally, that 
others will chiefly resemble the Worden, but will show 
a few characteristics of the Delaware, w^hile others 
again Avill chiefly resemble the Delaware, but will pos- 
sess a few characteristics of the Worden. It would not 
be surprising if we secure a vine having the vigor, 



Plant Breeding. 275 

productiveness and large fruit of the Worden, with the 
color and delicious flavor of the Delaware. This we may 
almost certainly acomplish if we continue our trials a 
sufficient time. In other words, we may often combine 
the good qualities of two varieties into a single variety 
by securing a number of cross- fecundations between 
the two (440), and 7^earing plants from the seeds thus 
formed. 

439. The Selection of Subjects for Crossing. If 
the object of crossing is simply to secure variation, as 
is sometimes the case with wild fruits, the parents 
should differ from each other as widely as posibble, 
provided only that they are capable of crossing freely. 
Crosses between allied species (hybrids (23) ), when this 
is possible, will be more likely to accomplish the object 
sought than between plants of the same species. 

If the object is the improvement of present varieties, 
the parents should be chosen with reference to the 
qualities desired in the new variety. For example, if 
it is desired to produce a hardy, late-keeping apple, 
of first quality any hardy variety that keeps well, what- 
ever its quality, may be crossed with any other hardy 
apple of first quality, whether it keeps poorly or well, 
though of two apples of first quality, the better keeper 
should be chosen. 

The plant breeder should first have a definite idea of 
the qualities he desires to secure in his proposed vari- 
ety, and should then study with much care the qualities 
of the varieties that he proposes to use as parents. The 
two varieties that contain the largest number of the 
desired qualities should be chosen. 



276 



Principles of Plant Culture. 



440. Cross-Fecundation is accomplislied through 
cross-pollination of the flowers (151) ; i. e., by placing 
pollen from the anthers of a flower of one of the varie- 
ties we desire to cross upon the stigma of the other 
variety. 

441. Preparing the Flower for Crossing. To pre- 
vent self-pollination (151) in perfect flowering plants 
(153), we emasculate (e-mas'-cu-late) the flowers, i. e., 
remove the anthers (143) before the pollen is mature. 
Prior to maturity, the anthers 
are generally pale in color and 
nearly smooth on the 
surface, with no visible 
pollen, but a little later, 
the pollen in most 
plants is visible as a 
bright yellow dust ad- ^ ,^^ r. ^- . . ^ 

Fig. l^l. Case of instruments and 

hering to the anthers, sacks for crossing plants. 
The anthers may be picked off with the forceps, or 
the filaments that support them may be clipped off* with 
the points of the scissors. They must generally be re- 
moved before the petals open (142). The latter may 
be gently opened with the forceps or needle, or they 
may be carefully removed. 

In the flowers of certain plants, as the pea, wheat and 
grape, pollination takes place before the blossom opens, 
hence in these plants it is necessary to emasculate the 
flowers very early. 

442. To Prevent Undesired Pollination, the blos- 
som should be inclosed by tying over it a sack of thin 
cloth or paper at the time of removing the anthers. 




Plant Breeding. 



277 



The sack will of course have to be removed for polli- 
nation, after which it should be promptly replaced. 

Pollination should be performed twenty-four to forty- 
eight hours after emasculation (441), the period de- 
pending upon the plant 
and the stage of develop- 
ment of the flower at the 
time of the latter opera- 
tion (150). Applying 
the pollen on two consec- 
utive days tends to in- 
sure success. 

The pollen is applied 
by placing an anther 
(143) containg mature 
pollen in direct contact 
with the stigma (144), 
or by removing some of 
the pollen upon the back of the point of a penknife or 
by means of a camel's-hair brush, and carefully appl}"- 
ing it to the stigma. A pin, of which the head has 
been flattened by hammering, inserted in the end of a 
stick, forms a convenient tool for this work. A slen- 
der stick of sealing wax drawn to a blunt point may be 
used in pollination by rubbing it on the sleeve to 
electrify it. 

The best time for pollination in the open air, is often 
in the early morning, since the atmosphere is then 
usually still, and contains little pollen from other flow- 
ers, which, if freely present in the air may vitiate the 
results of the pollination. 




Fig. 172. Emasculated flower in- 
closed in sack. 



278 Principles of Plant Culture. 

443. The After-Care of Crosses. After the last pol- 
lination, the blossom shonld again be inclosed until 
fecundation is effected, which is indicated by a rapid 
enlargement of the ovary. The paper sack may then 
be replaced by one of mosquito netting. This should 
be securely, but not too tightly, tied about the stem of 
the pollinated flower, to protect the inclosed fruit or 
seed-vessel from injury during growth and maturity, 
as well as to render it conspicuous. A label should be 
placed within the sack, or tied on with it, giving the 
name of the variety whence the pollen was secured. It 
is also desirable to record all the operations and ob- 
servations relative to the crossing. 

444. The Selection of Crossed Seedlings is a most 
important operation in producing new varieties by 
crossing. If none of the seedlings of the first genera- 
tion exhibit the desired qualities, those of a succeeding 
generation may exhibit them. The plants nearest the 
ideal should be selected, and all the seeds from these 
preserved for planting. When the ideal plant is 
found, it may be readily fixed by means of cuttings or 
grafts in plants generally propagated in this way. In 
those propagated by seed, several generations of cul- 
ture and selection may be necessary before the progeny 
will uniformly resemble the parent. 

The variations in the seedlings from two crossed 
varieties, and the kind of selection needed to fix the de- 
sired variations, are illustrated by the following dia- 
gram (Fig. 173). Let a represent the seeds from two 
crossed flowers A and B. The plants from these seeds 
will probably be quite variable, as is indicated by the 



Pla7it Breeding. 279 

divergent lines. Let us suppose the variation marked i 
to be the nearest the ideal form. The plants grown 
from i will again be quite variable in the second gen- 

A I , 



Fig. 173. Diagram illustrating the selection cf seedlings from 
a cross. 

eration h, but probably less so than in the first genera- 
tion. No plants of the second generation may be nearer 
the ideal type than those of the first generation, but 
we select the plant nearest to our ideal, and plant the 
seeds from this. Each succeeding generation may be 
expected to produce less of variability than the one 
before it. By and by, we may hope to secure a form 
that approaches our ideal and comes tolerably true 
from seed. 

445. Planting with Reference to Chance Crossings. 
Many valuable varieties have unquestionably arisen 
from accidental crosses between plants of different va- 
rieties that chanced to be growing in proximity. Profit- 
ing by this hint, varieties are sometimes planted near to- 
gether to favor self-crossing, a practice to be encouraged. 

446. Those Who Improve Plants are True Bene- 
factors. He who produces fruits or flowers for others 
works a transient good. But he who produces a variety 
of fruit or flower that is superior to any now known 
confers upon his race a permanent good. Until the 
introduction of the Wilson strawberry, the markets of 
our country were not supplied with this delicious and 



280 Principles of Plant Culture. 

wholesome fruit, because no known variety was suffi- 
ciently productive to be generally profitable, or suffi- 
ciently firm to endure long carriage. What a blessing 
was conferred upon us by a Mr. James Wilson, of Al- 
bany, N. Y. ! There are wild fruits in our copses to-day 
that are doubtless worthy of improvement, and in most 
of our fruits now under culture the development of 
superior varieties would greatly enhance their value. 
"The harvest truly is great, but the laborers are few\" 



The following books are recommended for reading in 
connection with the preceding chapter : Plant Breed- 
ing, Bailey; Variations of Animals and Plants Under 
Domestication, Darwin ; Propagation and Improve- 
ment of Cultivated Plants, Burbridge ; Origin of Culti - 
vated Plants, De Candolle. 



APPENDIX 



A SYLLABUS OF LABORATORY WORK. 

The laboratory exercises here outlined have been 
used by the author in his instructional work. 

Each student performs the exercises, so far as possi- 
ble, and the apparatus needed is provided. The stu- 
dent should be required to write a description of the 
work performed, stating results in every case, supple- 
menting his notes by drawings in special cases. 

It has not been found practicable to make the lecture 
room and laboratory work fully correspond as to time, 
but the effort has been made to do this as far as possoble. 

A greenhouse is very desirable for this kind of in- 
struction, and if the instruction is given in winter, a 
"garden house," i. e., a glass house inclosing an unob- 
structed area of garden soil is scarcely less important. 
But in the absence of these conveniences, a few win- 
doAv boxes will furnish a tolerable substitute. 

When the exercises are carried out during winter, 

considerable foresight is essential to have the needed 

materials in condition for use at the proper time. 

To stimulate ohservation{l) .* A few object lessons 
are given to encourage observation and correct reason- 
ing. A twig, an ear of corn or a potato tuber is given 
to each stucfent and all are encouraged to vie with each 
other in discovering new points, and in discussing the 
reasons therefor. This lesson is frequently repeated 
during the term. 



* The numbers in parenthesis refer to the paragraphs in the 
book. 
19 



282 



Principles of Plant Culture. 



c c. 



^mo 



■200 




Cell structure (12). The students examine the pulp 
of a mealy apple and of a potato, and cross-sections of 
a young bean plant, with simple lenses of rather high 
magnifying power. If a compound microscope is avail- 
able, many mounted objects illustrating the cell struc- 
ture of plants may also be shown. 

^ ^ — ~ N Absorption of water hy seeds (26.) 

S5 If For the exercise suggested by paragraphs 

26 and 27, a means of weighing and of 
measuring the volume of large seeds, as 
beans, with some degree of accuracy is 
needed. The device shown in Fig. 174 
answers this purpose, and one can be 
provided for each pair of students at a 
moderate cost. It consists of a graduated 
glass cylinder of 200 cubic centimeters 
capacity and a test tube about 6 inches 
long. For determining the volume, the 
cylinder is partly filled with water and 
the height to which the water rises is 
•loted. The seeds are then dropped in 
and the glass is shaken a little to re- 
move the air bubbles. The height of the 
water is again noted, when the difference 
in the two readings indicates the volume 
of the seeds in cuhic centimeters. For 
weighing the empty test tube is placed in 
the cylinder in the position shown (Fig. 
^~ "^ 174). The height to which the water 

Fig. 174. Device p^ggg jg ^hcu notcd, after which the seeds 

for weighing and -, n-iii j_j_xi j^i, 

determining the are dropped mto the test tube, and the 
volume of seeds. ^^^ ^f ^^le Cylinder is jarred sightly by 
tapping it with a pencil. The height of the water is 
again noted, when the difference in the readings indi- 
cates the weight of the seeds in grammes. 

The test tube should float in the center of the cylin- 
der, as shown, and the readings should be taken with 
the eye on a level with the surface of the water. 

Each student (or pair of students) is provided with 
the apparatus shown in Fig. 174, and with two bottles 



so 



■^-20 



Appendix— Sijllah US of Laboratory Work. 283 

of at least 100 cc. capacity, with corks. Each bottle 
should have a strip of white paper pasted vertically 
upon it to receive the name of the student and ether 
data. 

Each student Aveighs cr measures the volume of 50 
fresh seeds of the bean, pea or Indian corn in the man- 
ner described above. Having noted the weight or vol- 
ume in his note book, he pours the seeds, with the 
water, into one of his bottles, corks the latter and writes 
his name, with the date, on the paper pasted on its side. 
He then repeats the process with seeds cf the honey 
locust, yellow wood or some other seed that does not 
readily absorb cool water, and after recording the data 
in his notebcok, places the bottles in a warm place until 
the following day, when he again determines the weight 
or volume of the two kinds of seeds. The seeds placed in 
the first bottle will usually be found to have nearly cr 
quite doubled in size, while those in the second bottle 
have scarcely swollen at all. 

Next, show the class a sample of the second lot of 
seeds that have fully swollen from soaking in hot water. 
Impress upon their minds the fact that while most 
seeds readily absorb moisture at ordinary temperatures, 
a few kinds do not, and seeds of the latter class need 
to be soaked cautiouslv, before planting, in hot water 
{27 d.) 

The rate at which seeds absorb water depends 

a — Upon the water content of the medium (27). 
Weigh 3 samples of navy beans. Place one sample in 
water, a second in very damp earth anol the third in 
slightly damp earth. Weigh again the next day an.I 
compute the water absorbed by the three lots. 

h—Upon the point of contact. Weigh 2 samples of 
navy beans, placing one sample in moist soil without 
compacting, and the second in the same kind of soil well 
compacted about the seeds. Determine the water ab- 
sorbed by the two samples the next day. 

a— Upon temperature. Repeat the above with 2 sam- 
ples of navy beans, placing one lot in a temperature of 
80° to 90° F., and the other in 40° to 50° F. 



2S4 Principles of Plant Culture. 

Other means of using the apparatus shown in Fig. 
174 will occur to the thoughtful teacher. It may be 
used for determining specific gravities by dividing the 
weight by the volume. 

Germination (28). Give an exercise in testing seeds 
with the apparatus shown in Fig. 6. 

3Ioistu7'e essential to germination (29). Soak one lot 
of navy beans in water until they are fully swollen, 
and another lot until they are about half swoTen. Wipe 
the beans as dry as possible, put each lot into a bottle, 
cork the bottles, and set them in a warm room. The 
fully-sw^ollen beans will usually germinate promptly, 
while the others will not. 

Oxygen essential to germination (31). Perform the 
saucer experiment as described. 

Also place seeds of rice in two bottles, and add to 
each, water that has been boiled 20 minutes ; cover the 
water in one bcttle with a little olive- or cotton-seed oil. 
It is important to soak the seeds a short time in boiled 
water before putting them into the bottles to remove 
the air in contact with their seed-cases. 

Germination hastened hy soaking seeds (35). Soak 
seeds of Indian corn tw^o or three hours in warm water, 
and let each student place in a seed tester a sample of 
the soaked seeds, with one or two other seeds of the 
same kind that have not been soaked. 

Germination hastened hy mutilating the seed-case 
(36). This may be illustrated with seeds of the navy 
bean, in the seed-tester. 

The plantlet (40). Place seeds of radish, onions, etc.. 
loosely on the surface of a saucer filled with fine moist 
loam; keep the surface moist and note the repeated at- 
tempts of the hypccotyl to enter the soil. 

Seeds of the pumpkin family should, he planted fl-at- 
tvise (42). Plant seeds of the pumpkin or squash, ki 
the three positions indicated, in large greenhouse sau- 
cers. Cover each saucer with a pane of glass and 
place all in a warm room until the plantlets appear, 
after which note the number of each lot of seeds of 
which the seed-case appears above the surface. 



Appendix — Syllabus of Laboratory Work. 285 

Development of plantlets (44-46). Devote several ex- 
ercises to a study of the development of plantlets of 
the bean, pea, wheat, Indian corn, pumpkin, etc. To 
furnish the plantlets, seeds of the different sorts should 
be planted on several successive days, beginning at 
least 10 days in advance. 

Not all seeds should be deeply planted (47). Plant 
seeds of the bean, pea, Indian corn and wheat in 6-inch 
flower pots, at three different depths, viz., I/2 inch, 3 
inches and 6 inches from the bottom ; place the pots in 
a warm place for 3 weeks, after which carefully re- 
move the soil, noting the germination of the seeds in 
the different layers. 

Vigor of plantlet proportionate to size of seed (48). 
Plant large and small specimens of navy beans by them- 
selves, in greenhouse saucers, and permit them to ger- 
minate. The smaller seeds usually germinate earlier 
than the larger, but they produce more slender plant- 
lets, which soon fall behind the others in development. 

Plantlet visible in the seed (53). Boil samples of 
various kinds of seeds until they are fully swollen, 
after which require the students to dissect them and to 
seek out the plantlets. Lenses, needles and forceps are 
very useful in this work. 

The cotyledons a storehouse for food (59). Remove 
the cotyledons of some bean plantlets growing in a 
flower pot or saucer, leaving those of other plantlets 
intact. After a week note the result in the checked 
growth of the mutilated plants. 

Vascular bundles (67). Study these as sho^v^Ti in the 
stalk of Indian corn, in the leaf stems of various plants 
and in the leaf scars on the stems of plants. 

Cambium layer (68). Locate this in sections of 
various dicotyledonous stems, including the potato tu- 
ber; also note the absence of the cambium layer in 
monccotyledonous stems. 

Root-hairs (100). Study these as illustrated when 
seeds germinate in the seed tester. Germinated radish- 
seeds, left in the seed tester two or three days, usually 
develop root-hairs in great abundance. Also search out 



286 Principles of Plant Cultin^e. 

the root-hairs in potted plants. Emphasize the differ- 
ence between root hairs and root branches. 

Effects of transplanting on root hrancJiing (104). 
Study yonng' plants of lettuce, tomato, cabbage, etc , 
that have been pricked oft\ and compare their roots 
with those of others that have not been pricked off. 

Belation of roots to food supply (111). Plant seeds 
of the radish in saucers containing clean sand and pot- 
ting soil respectively, and when the seedlings have at- 
tained some size, wash out and examine the roots in 
the two soils. 

Root tuhercles (112). Study the roots of young 
clover plants of various ages, and note how early in th^ 
development of the plant the tubercles are discernible. 

Vnderground stems (114). Study the development 
of the potato plant from growing specimens, noting the 
points at which the tuber-bearing stems originate, antl 
the marked difference between these and the roots. 

Nodes and internodes (115). Observe the nodes in 
the stems of many plants, noting the relation of the 
diameter of the young stem to the length of the inter- 
nodes ; also note the undeveloped internodes near the 
terminus of the stem. 

Buds (127). Study specimens of leaf-buds from 
many plants, noting their structure, position, etc. 

Floirer-huds (132). Study the form and location cf 
the flower-buds in many plants, particularly in fruit 
trees. 

Parts of the flower- (140). Study the parts of the 
flower, explaining the function of each part. 

Perfect and imperfect flowers (153). Study these 
as produced by several different plants, particularly of 
the strawberry. 

Degree of maturity necessary to germination (162). 
Test seeds of Indian corn, pea, tomato, etc., that were 
gathered at varying stages of maturity. 

Seed vitality limited hy age (164). Test seeds of 
lettuce, parsnip, onion, etc., 1 year, 2 years and 5 years 
old, respectively. 



Appendix— Syllabus of Laboratory Wo7'k. 287 

Stratification of seeds (169). Perform the process, 
as described, in boxes or large flower pots. 

Sun-scald (185). Require each student to make n 
lath tree protector (Fig. 59). 

Winter protection of plants (201). Protect half- 
hardy shrubs by wrapping them with straw or covering 
them with earth. 

Foretelling frost (206). Devote an exercise to the 
use of the psychrometer and the computation of the 
dew point. 

Plant protector's (278). Require each student to 
make at least one plant protector, as shoAvn in Fig. 67, 
patterns for which are to be furnished. 

Kerosene Emulsion (294). Let each student make a 
given quantity of the kerosene emulsion after one of 
the formulas given. 

Spraying pumps (304). Give at least one exercise 
to the construction and use of spraying pumps and 
nozzles. 

Prevention of grain smuts (325). Require the stu- 
dents to treat a quantity cf oats Avith formalin as de- 
scribed. 

Bordeaux Mixture (329). Require each student to 
make a stated quantity of the Bordeaux mixture after 
the formula given. 

Propagation by seeds (344). Instruct the students 
in the use of the hand seed-drill and broadcast sower. 
Let them ascertain how much clover seed the broadcast 
machine is sowing per acre, by laying on the ground or 
floor several sheets of paper, exactly one foot square, 
painted with glycerine to catch the falling seeds. Hav- 
ing learned the average number of seeds deposited per 
square foot with a given rate of motion of the machine, 
let the students compute the number of seeds sown per 
acre, and reduce this to ounces. The number of clover 
seeds in an ounce may be ascertained by dividing an 
ounce of seed among the students for counting. 

Propagation by layers (349). Instruct the students 
in layering canes of the grape, and in mound-layering 
the stems of the gooseberry. 



288 Principles of Plant Culture. 

The hulh (352). Dissect bulbs of the onion, tulip^ 
lily, etc., ascertaining their structure and finding the 
embryo flowers. 

Tlie cold-frame (364). Require the students to make 
a drawing and write a description of a cold-frame, from 
a model furnished them. 

The hotbed (365). Let the students assist in making 
a hotbed after the plan described. Also let them note 
the temperature of the soil within the frame on sev- 
eral successive days after the bed is finished, and give 
them instruction in ventilating the hotbed. 

The propagating hed (368). Require the students to 
make a propagating bed in the greenhouse, after the 
plan described. 

Stem cuttings (373-375). Let the students make 
cuttings from the stems of the grape, currant, etc., 
and plant them, both in the propagating bed and in 
the garden. 

Root-cuttings (376). Give a lesson in making root- 
cuttings of the raspberry or blackberry, in packing the 
same for winter storage, and in planting them in the 
propagating bed and in the garden. 

Green cuttings (380-381). Give a lesson in making 
and planting cuttings of coleus, geranium, rose, etc., 
followed by instructions in the care of green cuttings 
in the propagating bed. 

Leaf cuttings (382). Give a lesson in making and 
planting leaf cuttings of the begonia. 

Grafting wax, etc. (387-389). Give a lesson in mak- 
ing grafting wax, grafting cord and grafting paper, 
as described. 

Whip-grafting (390-391). Give several lessons in 
whip-grafting including grafting both of the stem and 
of the root. 

Cleft grafting (392). Give one or two lessons in 
cleft grafting. 

Side grafting (393). Give a lesson in side grafting, 
as described. 

Budding (394). Give one or more lessons in bud- 
ding, as described. The bark on the stocks may be 



Appendix— Syllah us of Laboratory Work. 289 

made to peel by boiling, and trimmed bud sticks may 
be preserved for winter use, in dilute alcohol. 

Approach grafting (399). Give one exercise in ap- 
proach grafting as described. 

Packing jjlants for transportation (405). Devote one 
exercise to packing strawberry, cabbage or some other 
herbaceous plants, as described. 

Heeling-in, Replanting (408-410). Give one or more 
lessons in heeling-in and planting trees, as described; 
also at least one lesson in planting root grafts, cuttings 
and herbaceous plants as shown in Figs. 143-144; and 
a lesson in planting strawberry plants. 

Potting and shifting (412). Give two or more les- 
sons in potting and shifting as shown in Figs. 145-148. 

Pruning (427 etc.). Give one or more lessons in 
pruning by the methods described. 

Cross pollination (441). Give one or more lessons in 
cross pollination, as described. 



INDEX 



The NuDibt r's refer to Pages 



Accumulation of reserve food 
how to promote, 93. 

Acid phosphate, 157. 

Active state of protoplasm, 15. 

Adventitious buds, 87. 

Aeration of soil promoted by 
drainage, 70. 

Air-dry defined, 15. 

Air, roots require, 66, 67. 

Ammoniacal solution of copper 
carbonate, 184. 

Ammonium sulfate. 156. 

Animal parasites, 160. 

Animals, domestic defined, 11. 

Annular budding, 232. 

Anther, 97. 

Apparatus for applying insect- 
icides, 171. 

Appendix, 281. 

Apple, blight of, 180. 266; mag- 
got, 176; scab, 184. 

Approach grafting, 234. 

Army worm, 171. 

Arsenate of lead, 164. 

Arsenic compounds, 164; are 
deadly poisons, 165. 

Arsenic, white. 164. 

Arsenite of copper, 164; of 
lime, 158. 

Art and science defined, 9; how 
best learned. 10. 

Assimilation defined. 43. 

Baldridge transplanter, 247. 

Books recommended for col- 
lateral reading, 117, 188, 269, 
280. 

Bark bursting, 125. 

Bark, epidermis replaced by, 49. 

Bemis transplanter 247. 



Birds, damage from, 160, 161. 

Black-heart, 124. 

Black knot of plum, 180, 266. 

Black rot of grape, 184. 

Blanching of vegetables, 149. 

Blight of apple and pear, 180. 
266. 

Bloom defined, 49. 

Board screen for shading young 
plants, 146. 

Bordeaux mixture, 183; dis- 
eases prevented by, 184. 

Borers in trunks of trees, 163, 
175. 

Branches development of, from 
lateral leaf -buds, 87; of trees, 
to prevent splitting down in 
pruning, 262. 

Branching stimulated by 

pinching, 82. 

Branching of roots, condi- 
tions affecting, 74; how stim- 
ulated, 75. 

Breeding defined, 17. 

Brittleness of plant tissues. 60. 

Broom rape of hemp and to- 
bacco, 178. 

Brush screen for shading 
plants, 146. 

Bud. 219, 230. 

Budding, 221, 231; annular, 231; 
ring 231; shield, 231; success 
is dependent on, 231; T, 231. 

Budding knife, 233. 

Buds, 86; adventitious, 87. 

Buhach, 166. 

Bulb, 197. 

Bulbels, 198. 

Bulblets, 198. 

Bundling trees for transporta- 
tion, 240. 



292 



Index. 



Cabbage caterpillar, 166; mag- 
got, 174; club-root of, 182. 

Calcium, part played by in 
plant, 45. 

Callus how formed, 56. 

Calyx, 96. 

Cambium layer, 53; from dif- 
ferent plants may unite, 54. 

Carbon, proportion of in vege- 
table material, 44; sources of, 
in plants, 43. 

Caulicle, 33. 

Cauliflower heads to be shaded 
from sunlight, 146. 

Caustics, destroying insects by, 
163. 

Cell division, 15. 

Cells, guard, 50; palisade, 49; 
some properties of, 14. 

Cellular structure of living be- 
ings. 13. 

Chili saltpeter, 156. 

Chinch bug, 170. 

Chlorid of potash, 157. 

Chlorophyll defined, 41; forms 
only in light, 42; iron essen- 
tial to formation of, 45; no 
food formed without, 42. 

Chlorophyll bodies, 42. 

Cion, 219, 221. 

Cion grafting, 221. 

Classification defined, 18; il- 
lustrated, 19. 

Cleft grafting, 226. 

Close-pollination, 102. 

Clouds tend to avert frost 
134. 

Clover, dodder of. 179; tuber- 
cles on roots of, 79. 

Club-root of cabbage, 182. 

Codling moth, 176. 

Cold air drainage, 134. 

Cold, excessive, how affecting 
the plant, 121, 

Cold-frame. 203. 

Composite flowers, 98. 

Conditions affecting power cf 
plants to endure cold, 122. 

Cooling the plant, immediate 
effect of, 121. 



Copper carbonate ammoniacal 
solution of, 184. 

Corm, 198. 

Corn, detasseling, 263; smut, 
180. 

Corolla, 96. 

Cotyledons defined, 35. 

Covering of seeds in planting, 
why important, 33. 

Cracks in fruits and vegeta- 
bles due to excessive moist- 
ure, 140. 

Crop, affected by age of seed. 
110; a growing, tends to con- 
serve fertility, 159; removal 
of, tends to reduce plant food 
in the soil, 153; rotation of 
economizes plant food, 158. 

Crops, trees detrimental to 
neighboring, 59. 

Crossed seedlings, selection of, 
278. 

Crosses, after care of, 278; and 
hybrids defined, 20; varia- 
bility of, 21. 

Cross fecundation, how accom- 
plished, 276. 

Crossing, selection of subjects 
for, 275; variation produced 
by, 274. 

Crossings, planting with refer- 
ence to chance 279. • 

Cross-pollination, 102; advan- 
tage of, to plants, 102. 

Cucumber beetle, 162; screen- 
covered frame for hills of, 162. 

Cucurbitae, provision in, to aid 
plantlet to emerge from seed- 
case, 33, 34. 

Cultivation tends to prevent 
drought, 143. 

Culture, aim cf. 11; deals with 
life, 12; defxned, 10; plants 
have improved under, 270; 
variation produced by, 273. 

Curculio 176. 

Currant worm, 166. 

Current, evaporation of. 60; of 
prepared food, 62. 

Cuticle defined, 49. 



Index. 



293 



Cutting- defined, 200; essential 
characters of a, 201. 

Cuttings, conditions favoring 
growth of, 201; from active 
plants, 214; from dormant 
plants, 209; from dormant 
stems, 211; of woody plants, 
preferably made in autumn, 
115; parts of plants to be 
used for, 200; planting in au- 
tumn, 211; storage of. 210; 
tool for planting, 246. 

Cuttings, green, 214; especial 
care necessary in propagat- 
ing plants from, 215; how 
made from herbaceous plants, 
217; how made from woody 
plants, 217; to be potted as 
soon as roots are formed, 216. 

Cuttings, leaf, propagation by, 
218. 

Cuttings, mallet, 212. 

Cuttings, root, propagation by, 
213. 

Cuttings, stem, 211; to make 
and plant, 212. 

Cutworms, 162. 

Dalmatian insect powder, 166. 

Damage from cold prevented by 
protecting with non-conduct- 
ing material, 128. 

Damping off, 216. 

Darkening of wood, 124. 

Deflowering defined, 253. 

Defruiting defined, 253. 

Density, pruning for, 259. 

Depth of roots in soil, 75. 

Destruction of terminal buds 
by cold. 124. 

De-tasseling, 253, 263. 

Devices for transplanting, 245. 

Dew point, how to compute the 
132; table for computing, 133. 

Dibber, 246. 

Dicotyledons defined, 36. 

Diffusion, law of, 47. 

Dioecious flowers, 102. 

Disbudding defined, 253; trees, 
259. 



Disease defined, 13. 

Distal defined, 80. 

Dodder of clover and flax, 179. 

Domestic plants and animals 
defined, 11. 

Dormant state of protoplasm, 
15. 

Drainage promotes soil aera- 
tion, 70; required by potted 
plants. 70. 

Dressing defined, 253. 

Drought causes toughness of 
plant tissue, 143; cultivation 
a preventive of, 143; mulch- 
ing a preventive of, 144; tends 
to hasten maturity, 142. 

Drying kills plant tissues, 144. 

Duration of germinating power. 
108; of seed vitality, condi- 
tions affecting, 109. 

Electric light, use of, in glass 
houses, 149. 

Elements esential in plant 
food, 44; part played by dif- 
ferent, 44. 

Emasculation of flowers, 276. 

Embryo defined, 40. 

Endosperm defined. 40. 

Environment defined, 10; fac- 
tors of, 118. 

Epidermis defined, 48; replaced 
by bark in older stems, 49. 

Evaporation current, 60. 

Evergreen trees destroyed by 
untimely warm weather in 
spring, 119. 

Evolution, theory of, 21. 

Factors of environment, 118. 
Families, how formed, 18. 
Farm manure, 158. 
Fecundation, 100; cross, how 

accomplished 276. 
Feebleness defined, 12. 
Ferns, how grown from spores, 

39. 
Fertilization, 100. 
Fertilizer requirements of crops, 

158. 



294 



Index. 



Filament, 97. 

Fir tree oil, 170. 

Fibro-vascular bundles, 51. 

Fixing desirable variations, 271. 

Flax, dodder of, 179. 

Flea beetles, 168. 

Flower, 95; certain parts of, 
often wanting, 98; parts of 
the, 95; parts of, vary in 
form in different species, 98. 

Flower-buds, 88; conditions af- 
fecting formation of, 91; de- 
stroyed by cold. 126; how dis- 
tinguished from leaf-buds, 
88; ringing often causes for- 
mation of, 94, 265. 

Flowering and fruiting, root 
pruning to promote, 264. 

Flowering, glumes, 100. 

Flowering. pinching to pro- 
mote. 263. 

Flowers composite, 98; espe- 
cially sensitive to cold, 127; 
of the grass family, 99; tend 
to exhaust the plant, 95. 

Flowers and fruit, obstructing 
growth current to promote, 
265; pruning for, 263. 

Flow of sap in spring, 61. 

Food, current of prepared, 62; 
elements of, most likely to 
be deficient in the soil, 45; 
insufficient dwarfs the plant, 
153; materials of, how dis- 
tributd through plant, 47; re- 
serve, 15; storage of re- 
serve, 64; use of reserve 64. 

Food preparation the function 
of leaves, 82. 

Food supply, relation of rcots 
to, 78; unfavorable, effect cf. 
on plant, 151. 

Formaldehyd, 181. 

Formalin treatment for grain 
smut, 181. 

Formative pruning, 256. 

Formula for Bordeaux mix- 
ture, 183. 

Formulas for kerosene emul- 
sion, 168; for resin washes', 168. 



Freezing of plants favored by 
much water in plant tissue 122. 

Freezing, severe, may split 
open tree trunks 125. 

Frost, conditions that tend to 
avert, 134; how foretold, 131; 
plants injured by, how saved 
from serious damage, 124; 
liability to, depending com- 
paratively little upon lati- 
tude, 135; localities most sub- 
ject to, 135; methods of pre- 
venting injury by, 136. 

Frozen tissues, treatment of, 
124. 

Fruit, 104; or flowers, pruning 
for, 263; thinning of, 105, 263. 

Fruitfulness promoted by re- 
stricting growth current 63. 

Fruiting. obstructing growth 
current to promote, 265; root 
pruning to promote, 264. 

Fruits and vegetables, cracks 
in. caused by excessive moist- 
ure, 140; rarely develop with- 
out fecundation, 104; ripen- 
ing tf. 106. 

Fungi, 179; endophytic, 181; 
epiphytic, 181; methods of 
controlling, 180. 

Fungicides, 180; various, 182. 1S5. 

Funguous diseases. need of 
consulting specialists in, 185. 

Gathering and storing of seeds. 
106. 

Genera, how formed, 18. 

Generic name defined. 20. 

Genus, how formed, 18. 

Germinating power, duration 
of, 108. 

Germination defined, 24; de- 
pendent on stage of matur- 
ity of seeds. 106; hastened by 
compacting soil, 28; hastened 
by mutilating seed-case, 30; 
hastened by soaking seeds, 
29; in water, 27; moisture es- 
sential to. 25; not hindered 
by light. 32; oxygen essential 



Index. 



295 



Germination — 

to. 26; promptness in, im- 
portant, 28; requisites for. 
28; retarded by excess of 
water, 29; seed-case in, 33; 
temperature at which, takes 
place, 26; time required for, 
32; warmth essential to, 25; 
when completed, 25. 

Germinations, earlier, form 
more vigorous plantlets, 38. 

Girdling-, killing trees by 63. 

Glumes, 99. 

Gooseberry mildew, 184. 

Gophers, damage from, 161. 

Gormands on fruit trees, 140. 

Graft, 219. 

Grafting, approach. 234, 221; 
cion, 221; cleft, 226, 224; cord, 
224; herbaceous, 228, 234; how 
possible 54; objects of. 220; 
paper, 224; plants uniting 
by, 220; propagation by, 219; 
root, 221; side, 228; top, 226; 
veneer, 229; wax, how made, 
222; whip, 224. 

Grafts, whole root, 226. 

Gramineae, flowers of, 99. 

Grape mildew, 182. 

Grass family .flowers of. 99. 

Grasshoppers, 171. 

Greenhouse, 205; heating de- 
vices for, 206. 

Growing point defined, 51. 

Growth by cell division, 15, 
cutting back new, to pro- 
mote flowering, 264; decline 
of. 111; deflned, 15; in di- 
ameter, of stems, 54; of 
roots in length, 71; pruning 
for, 263; retarded by insuffi- 
cient moisture in soil, 142; 
tardy starting of, after trans- 
planting 251; water neces- 
sary to, 45. 

Growth current, obstructing, to 
promote flowering and fruit- 
ing, 265; restriction of, pro- 
motes fruitfulness, 63. 

Guard cells, 50, 51. 



Hardiness defined, 13; depend- 
ent on degree of dormancy, 
114. 

Healing of wounds, 56. 

Health defined, 13. 

Heat, excessive, how affecting 
plants 118. 

Hedge shears, 267. 

Heeling-in plants, 241. 

Hellebore powder, 166, 167. 

Hemp, broom rape of, 179. 

Herbaceous grafting. 228, 234. 

Herbaceous stems defined, 53. 

Heredity and variation, 16. 

Hermaphrodite fiowers, 102. 

Hoarfrost, cause of, 130. 

Horizontal extent of roots, 76. 

Host (of parasites) defined. 21. 

Hotbed, the, 204. 

Hotbeds require care in ven- 
tilation, 70. 

Hot water, for destroying in - 
sects, 170. 

Humidity, methods of con- 
trolling, 208. 

Hybrids and crosses defined, 20. 

Hydrocyanic gas, 169. 

Hydrogen, source of, in plants, 
44. 

Hyphae, 180. 

Hypocotyl, defined, 32; devel- 
ops differently in different 
species, 36; roots start from, 
35; seeds in which it length- 
ens must be planted shal- 
low. 36. 

Ice often destroys low plants. 

127. 
Immature vs. ripe seeds, 107. 
Imperfect fiowers, 103. 
Implements, for pruning, 267; 

for transplanting, 245, 246, 

247. 
Improvement possible through 

plant variability, 271. 
Inaividuals defined, 18. 
Injury by cold, methods of 

averting, 127. 



296 



Index. 



Insecticides, 163; apparatus for 
applying, 171; use of, 173. 

Insects beneficial, 162; bur- 
rowing, 174; destroying by 
poisons or caustics, 163; eat- 
ing-insects, 173; hand-pick- 
ing, 163; injurious, life his- 
tory of, 1(8; leaf-eating, 174; 
ravages, method of prevent- 
ing, 162; repelling, by means 
of Oii-ensive odors, 163; root- 
eating, 174. 175; sucking, 173, 
177. 

Insects trapping, 162. 

Internodes, defined, 80; stem 
lengthens by elongation of, 
81; ultimate length of, 81. 

Iron essential to formation of 
chlorophyll, 45. 

Irrigation, 144. 

Kainit, 157. 

Kerosene, applied with water, 
168; as an insecticide, 168; 
emulsion, 168. 

Killing trees by girdling, 63. 

Knife, budding, 233; grafting, 
223; pruning 267. 

Knowledge, application of, es- 
sential to success, 9. 

Lath screen fcr shading plants, 
145. 

Leaf -buds, 88; comparative 
vigor of, 91. 

Leaf cuttings, propagation by, 
218. 

Leaf development, importance 
of, 83. 

Leaf fall, time of, an index of 
wood maturity, 113. 

Leaf-eating insects, 174. 

Leaf miners, 175 176. 

Leaves, 82; are usually short- 
lived, 85; comparative size of, 
84; function of, 82; manurial 
value of, 85. 

Leguminous plants enrich the 
soil with nitrogen, 79, 156. 

Lenticels, 51. 



Lever shears, 268. 

Life, culture deals with, 12. 

Life, what is it? 12. 

Lifting large trees, 238. 

Lifting the plant, directions 
for. 239. 

Light does not hinder germina- 
tion, 32. 

Light, unfavorable, how affect- 
ing the plant, 145. 

Living beings, cellular struc- 
ture of, 13. 

Localities most subject to un- 
timely frosts, 135. 

Locusts, 171. 

London purple, 165. 

Low plants often destroyed by 
ice, 127. 

Magnesium, part played by, in 
plant, 45. 

Mallet cuttings, 212. 

Manure increases water-hold- 
ing capacity of soil, 45. 

Manurial value of leaves 85. 

Maturative pruning, 266. 

Maturity of plants, influence of 
drought on, 142. 

Maximum defined, 25. 

Mealy bug, 170. 

Melons, screen-covered frame 
for protecting hills of, 162. 

Mice, damage from, 160. 

Minimum defined, 25. 

Moisture, an enemy to stored 
seeds, 109; essential to ger- 
mination, 25; excessive, caus- 
ing cracks in fruits and 
vegetables, 140; excites root 
growth 66; excessive, in air, 
injurious to plants, 141; in- 
sufficient, in air causing ex- 
cessive transpiration, 142; in- 
su.- cient. in soil retards 
growth, 142. 

Monocotyledones defined, 36. 

Monoecious flowers, 102. 

Mound-layering, 195. 



Index. 



297 



Mulching, tends to prevent 
drought, 144; transplanted 
stock, 250. 

Muriate of potash. 157. 

Names, scientific, why used, 19. 

Nitrates in the soil, sources 
of, 154. 

Nitrification, 154, 155. 

Nitrogen, 154, 155; in proto- 
plasm, 45; in rain and snow, 
155; sources of, in plant, 45; 
stimulates growth, 152. 

Nodes defined, 80. 

Northerly exposure least try- 
ing to plants in winter, 129. 

Noiching. 253, 265. 

Nursery trees benefited by 
transplanting, 76. 

Oats, treatment of seed for 
prevention of smut, 181. 

Objects of grafting. 220; of 
pruning, 256. 

Oedema in plants, caused by 
excessive watering, 139. 

Onion mildew, 182. 

Optimum defined, 25. 

Orange rust, 180. 

Organic manures, partially de- 
composed, act more promptly 
than fresh ones, 155. 

Organic matter, importance of, 
in soil, 69. 

Osmosis defined, 61. 

Ovary, 97. 

Overbearing should be pre- 
vented, 105. 

Ovule, 97. 

Oxygen, essential to germina- 
tion 26; necessary to life of 
roots, 66; source of, in 
plants, 44. 

Oyster-shell bark-louse, 168. 

Packing plants for transporta- 
tion, 239. 
Pales, 100. 
Palets, 100. 
Palisade cells, 49. 
20 



Parasites, animal, 160; defined. 
21; fiowering or phaneroga- 
mic, 178; funguous, 179; in- 
jurious, 159; vegetable, 178, 

Parenchyma, 51. 

Paris green, 164. 

Pear, blight of, 180, 266. 

Peeling the stems of trees, 
57, 265. 

Perfect flowers, 102. 

Persian insect powder, 166. 

Petals, 96. 

Phosphorus, 157; part played 
by, in plants, 45. 

Picturesqueness, pruning for, 
258. 

Pinching defined, 252; stimu- 
lates branching, 82; to pro- 
mote flowering. 263. 

Pistil. 97. 

Pith, 52. 

Plant food, elements in, 44; ele- 
ments of, likely to be defi- 
cient, 45; from soil must be 
dissolved by soil water, 44; 
in soil, reduced by crop 
growing, 153; sources of, 43. 

Plant improvement, how ex- 
plained, 270. 

Planting, too close, causes de- 
ficient light, 148; trees, direc- 
tions for. 242 245; with ref- 
erence to chance crossings, 
279; with reference to polli- 
nation, 103. 

Plantlet, inner structure of, 48; 
may need help to burst seed- 
case, 34; principal parts of, 
41; vigor of, proportionate to 
size of seed, 38; visible in 
seed, 40. 

Plant life, round of, 22, 116. 

Plant manipulation. 189; pro- 
pagation, 189. 

Plant, directions for lifting 
the. 237; removing the, 239. 

Plant tissues, brittleness of, 
60; killed by drying, 144; 
toughness of, caused by 
drought, 143. 



298 



Index. 



Plants, abnormal development 
of due to Insufficient light, 
147; affected by unfavorable 
environment, 118; difference 
in water requirements of, 139; 
distance apart for growing, 
83; domestic, defined, 11; 
have improved under culture, 
270; heeling-in, 241; injured 
by excessive water, 139; af- 
fected by parasites, 159; only 
can prepare food from min- 
eral substances. 43; packing 
for transportation, 239; pot- 
ted, require drainage, 70 
potting and shifting, 247 
power of, to endure cold, 122 
preparation of, for replant- 
ing, 242; rapid-growing, re- 
quire much water, 138; shad- 
ing after transplanting, 146; 
those who improve, are true 
benefactors, 279. 

Plants under glass liable to 
suffer from deficient light, 
148; need of rest of, 113; 
not to be sprinkled in bright 
sunshine, 119; plants unpack- 
ing, 241; variability of, 271; 
washing the roots of pud- 
dled, 242; watering of potted, 
70, 138; watering the roots of 
recently transplanted, 250; 
screens for shading, 145, 146. 

Plum, black knot of, 180, 266. 

Plum curculio, 176, 177. 

Plumule, 41. 

Poisons, destroying insects by. 
163. 

Pollen. 97; appearance of ma- 
ture, 276; applying, 277; to 
prevent access of undesired, 
276. 

Pole shears, 268. 

Pollination, 101; in many plants 
dependent on wind, 151; 
planting with reference to, 
103; to prevent self, 276; 
when should it be performed, 
277, 



Potash, caustic, 168. 

Potassium, 157; assists in food 
preparation, 45; -sulfid solu- 
tion, 184. 

Potato, beetle. 163, 165; blight 
of, 184; foliage of, injured by 
sun heat, 121. 

Potato plant, illustrated, 79. 

Potatoes, knobby, 141. 

Potted plants require drainage, 
70; watering of, 70, 138, 139. 

Potting, and shifting, 247; soil 
248. 

Powdery mildews, 185. 

Preparation of plants for re- 
planting, 242. 

Prepared food, current of, 62. 

Pricking off seedlings, 76. 

Principle of selection, 17, 270. 

Propagating bed, the, 207. 

Propagation by cuttings, 200; 
by detached parts, 196; by 
division, 181, 190; by di- 
vision of the crown, 196; 
by grafting, 219; by layers. 
195; by parts intact 192; by 
sections of the plant, 199; by 
seeds, 190; by specialized 
buds, 196; by stolons, 194; by 
suckers, 193; methods of, 190. 

Prosenchyma, 51. 

Protective pruning, 266. 

Protoplasm, active state of, 15; 
dormant state of, 15; some 
properties of, 15. 

Proximal defined, 80. 

Pruning, defined, 252; for den- 
sity, 259; for flowers or fruit. 
263; for growth, 263; for pic - 
turesqueness, 258; for slen- 
derness, 258; for stockiness, 
258; for strength, 260; for 
symmetry, 256; formative, 
256; implements, 267; insuf- 
ficient, prevents formation of 
fruit buds, 149; -knife, 267; 
maturative, 266; objects of, 



256 
267 
267 



protective, 266; -saw, 
season for, 254; -shears, 
stimulative, 262; where 



Index. 



299 



Pruning — 

and how to make the cut in, 
254. 

Psychrometer, sling, 131. 

Puddled plants, washing roots 
of, 242. 

Puddled soil defined, 26; pre- 
vents germination, 27. 

Puddling the roots of trees, 240. 

Pumpkin, provision in to aid 
plantlet to emerge from seed- 
case, 34, 35. 

Pyrethrum powder, 166. 

RabL...s, damage from, 161. 

Radicle, 33. 

Raspberry pruning hook. 268. 

Rate of root growth, 78. 

Reduced vigor, tendencies of, 13. 

Reducing the tops of trees prior 
to planting, 242. 

Removing the plant, 239. 

Reproduction defined, 16; rela- 
tion to growth, 16; sexual 
and non-sexual, 16. 

Reserve food, 15; how plants 
use, 64; how to promote ac- 
cumulation of, 91; storage of, 
64. 

Resin washes, 168. 

Rest period. 111; not peculiar 
to temperate zones, 112; 
plant processes may not en- 
tirely cease during, 115. 

Reversion. 271. 

Richards' transplanting tools, 
246. 

Ring-budding, 231, 234. 

Ringing, defined, 253; often 
causes formation of flower- 
buds, 94. 

Ripening of fruits, 106. 

Root, and the soil, 65; office of, 
65; originates in stem, 65; 
starvation, 63. 

Root branching, conditions af- 
fecting, 74. 

Root branching, how stimu- 
lated, 75; should be encour- 
aged. 74. 



Root cap, 71. 

Root cuttings, 213, 214. 

Root grafting, 225. 

Root grafts, tools for planting, 
246. 

Root growth, excited by moist- 
ure, 66; rate of, 78. 

Root-hairs absorb water with 
considerable force, 73; apply 
themselves to soil particles, 
72; 70; dissolves soil parti- 
cles, 72; nature of, 49, 71; 
show need of roots for air, 
67. 

Root killing of trees, 126. 

Root pruning to promote flow- 
ering and fruiting 264; stim- 
ulates root branching, 75. 76. 

Root tubercles, 79. 

Roots, depth of, in soil, 77; de- 
stroyed by excessive water 
in soil, 137; growth of in 
length, 71; horizontal extent 
of, 76; of trees, puddling, 
i40; only youngest active in 
aosorption, 74; oxygen neces- 
sary to life of, 66; properly 
and improperly planted, 243; 
relation of, to food supply, 
78; replanting the, 242; start 
from hypocotyl, 35; trimming 
of, prior to planting, 242; 
washing, of puddled plants, 
242; wetting, prior to plant- 
ing, 243. 

Root-tip, how penetrates the 
soil, 70. 

Root-tips, formation of should 
be encouraged, 74. 

Rotation of crops, 158. 

Rose beetle, 163. 

Rosin washes, 168. 

Round of plant life, the 22. 
116. 

Rust of blackberry, 180. 

Sacking the roots of trees, 239. 

Saltpeter, 157. 

Sap defined, 46. 

Sap, flow of in spring, 61. 



800 



Index. 



Sap-sprouts on fruit trees, 140. 

Saw, pruning-, 268. 

Science and art defined, 9; how 
best learned, 10. 

Scientific names, why used, 20. 

Scion, 220. 

Screens for sliading plants, 
145. 146. 

Season for pruning, 254. 

Seed, 104; age of, as affecting 
the resulting crop, 110; ma- 
turing of, injures fodder 
crops, 105; plantlet visible in, 
40; production of exhausts 
plants, 104; selection. im- 
portance of, 273; vigor of 
plantlet proportionate to size 
of, 38; vitality, conditions af- 
fecting duration of, 108. 

Seed-case defined, 23; influence 
of on absorption of water by 
seeds, 23; in germination, 33; 
is useless after germination 
commences, 33; plantlet may 
need help to burst, 34. 

Seeding, prevention of, pro- 
longs the life of plants, 105. 

Seed-leaves defined, 36. 

Seedlings, pricking off young, 
76; selection of crossed. 278; 
variation produced by grow- 
ing. 274; young, injured by 
unobstructed rays of sun. 145. 

Seeds absorb water by contact, 
22; a few germinate in water, 
27; drying of, how affecting 
their vitality, 110; earlier 
germinating, form more vig- 
orous plantlets, 38; gathering 
and storing of. 106; germina- 
tion hastened by mutilating 
seed-case, 30; how deep 
should they be planted? 38, 
191; immature vs. ripe. 107; 
in which hypocotyl lengthens 
must be planted shallow, 36; 
of pumpkin family should be 
planted flatwise, 34; rate at 
which they absorb water, 22; 
should be tested before plant- 



Seeds— 
ing. 31; should not be planted 
until soil becomes warm, 29; 
stored, moisture an enemy 
to, 109; stratiflcation of. 111; 
very small, should not be 
covered, 39, 191; vitality of, 
limited by age, 108; why 
cover, at planting, 33; why 
they fail to germinate, 30; 
testing, directions for, 31; 
-tester described. 31. 

Selection a means of fixing 
variations, 272; of crossed 
seedlings, 278; of seed, im- 
portance of, 273; of subjects 
for crossing, 275; principles 
of, 17, 270. 

Self pollination, 102. 

Sepal, 96. 

Sexual reproduction, 16. 

Shading plants after trans- 
planting. 251. 

Shears, hedge, 269; lever, 269; 
pole, 268; pruning, 268. 

Shed screen for shading plants, 
145. 

Shield budding, 231. 

Shifting plants, 248. 

Side grafting, 228. 

Sifting box for applying in- 
secticide powders, 171. 

Slenderness, pruning for, 258. 

Slips, 214. 

Slugs. 162. 

Smut of the small grains, 181; 
of corn, 180; of onion 181. 

Snails, 162. 

Sodium nitrate, 156. 

Soil, and the root, 65; a scene 
of constant changes, 68; com- 
pacting, about seeds hastens 
germination, 28; compacting 
wet, may prevent germina- 
tion, 27; depth of roots in, 
77; how penetrated by root- 
tip, 70; ideal, for land plants. 
68; importance of organic 
matter in, 69; needs ventila- 
tion, 69; particles of. dis- 



Index. 



301 



Soil- 
solved by root-hairs, 72; for 
potting-, 248; puddled, defined, 
26; puddled, prevents germi- 
nation, 27. 

Soil aeration promoted by 
drainage, 70; promotes soil 
fertility, 155. 

Species, 18. 

Specific names defined, 20. 

Spikelet, 99. 

Splice grafting, 224. 

Splitting- down, to prevent 
branches from, 262. 

Spore germination favored by 
moisture, 185; prevention of. 
181. 

Spores defined, 39; non-sexual, 
16; of ferns, how planted, 39. 

Spraying outfit, steam, 173. 

Spray pump, 172. 

Sprinkling of plants under 
glass to be avoided in bright 
sunshine, 119. 

Squash, provision in, to aid 
plantlet to emerge from seed- 
case, 34; bug, 173; -vine 
borer, 163. 

Stable manure, 158. 

Staking trees to prevent shak- 
ing by the wind. 245. 

Stamens, 97. 

Starvation of roots, 63. 

Stem and root development de- 
pendent on number of leaves, 
83. 

Stem defined. 79. 

Stem, fastest elongation of, 82; 
how lengthens, 81; root origi- 
nates in, 65; vital part of 
woody, 55. 

Stem cuttings, 211; how plant- 
ed, 212; proper length of, 212. 

Stems, how they increase in 
diameter, 54; underground, 80. 

Stigma, 97. 

Stimulative pruning, 262. 

Stocks for grafting, 225. 

Stockiness, pruning for, 258. 

Stoma defined, 50. 



Stomata defined, 50. 

Storage of cuttings, 210; of re- 
serve food, 64. 

Stratification of seeds. 111. 

Strawberry, perfect and im- 
perfect flowers of, 103. 

Strength, pruning for, 260. 

Striped cucumber beetle, 162. 

Subjects for crossing, selection 
of, 275. 

Style. 97. 

Suckering defined, 253. 

Sulfate of potash, 157. 

Sulfur, part played by in 
plants, 45. 

Sun heat injurious to young 
seedlings, 145. 

Sun-scald, 120. 

Superphosphate, 157. 

Symbiosis, 154. 

Table for computing dew point, 
133; showing duration of seed 
vitality, 108; showing germi- 
nating temperatures of seeds, 
26. 

Tarred-paper cards, tool for 
cutting, 175. 

T-Budding, 2ol. 

Temperature as affecting plant 
growth, 118; fatal to proto- 
plasm, 119; influence of on 
absorption of water by seeds, 
23; methods of controlling, 202. 

Tenderness defined, 13. 

Terminal buds, pinching of, ef- 
fect on wood maturity, 128; 
destruction of, by cold, 124. 

Theory of evolution, 21. 

Thermal belts, 135. 

Thinning fruit, 105, 263. 

Time, most favorable for trans- 
planting, 236. 

Tobacco, broom rape of, 178; 
decoction of, for destroying 
aphide. 167; smoke for de- 
stroying insects, 167; fluid 
extract of, 167; topping, 253, 
263; -worm, 163; frenching, 
139. 



302 



Index. 



Tomato worm, 163. 

Tongue grafting, 224. 

Tool for injecting poisonous 
liquids, 174; for cutting paper 
cards, 174. 

Top grafting, 225. 

Topping, defined, 253; tobacco, 
263. 

Transpiration, amount of, 59; 
conditions affecting, 58; cur- 
rent, 60; defined, 58; exces- 
sive, 59; excessive, caused by 
insufficient moisture in the 
air, 142; increases with de- 
gree of heat, 118. 

Transplanted plants, shading. 
251; watering, 250. 

Transplanted stock, tardy 

starting of, 251. 

Transplanter, Baldridge, 247; 
Bemis, 247. 

Transplanting, 235; benefits 
nursery trees. 76; endured 
best by vigorous plants, 236; 
most favorable time for, 236; 
stimulates root branching, 
75; devices for, 245. 

Transplanting tools, Richards', 
246. 

Trapping insects, 162. 

Tree trunks split open by se- 
vere freezing, 125. 

Trees, bundling for transporta- 
tion, 239; detrimental to 
neighboring crops, 59; direc- 
tions for planting 243; kill- 
ing by girdling, 63; lifted or 
lowered to accommodate 
grading, 238; lifting large, 
237; nursery, benefited by 
transplanting. 76; puddling 
roots of, 240; reducing top of, 
prior to planting, 242; sack- 
ing roots of, 241; staking, to 
prevent shaking by wind, 245. 

Trimming defined, 253; roots 
prior to planting, 242. 

Tuber, the, 198. 

Tubercles on roots. 78. 

Turn of the year, 115. 



Underground stems, 80. 
Unhealed wounds introduce de- 
cay, 255. 
Unisexual flowers, 102. 
Unpacking plants, 241. 

Variability of offspring of 
crosses and hybrids, 20; of 
plants, 271. 

Variation, and heredity, 16; 
how can we produce, 273; 
may take place in any direc- 
tion, 17; produced by cross- 
ing, 274; produced by cul- 
ture, 273; produced by grow- 
ing seedlings, 274. 

Variations, how to fix desir- 
able, 271; not always perma- 
nent, 271. 

Varieties, 18; origin of culti- 
vated, 270. 

Vascular bundles defined, 51. 

Vegetables, cracks in caused 
by excessive moisture, 140. 

Ventilation, hotbeds require 
care in, 70; soil needs, 69. 

Veneer grafting, 229. 

Vigor defined, 12; of plantlet 
proportionate to size of seed, 
38; tendencies of reduced, 13. 

Vital part of woody stems, 55. 

Warmth essential to germina- 
tion, 25. 

Washing the roots of puddled 
plants. 242. 

Water, adequate supply of most 
importance, 45; excess of, re- 
tards germination, 29; ex- 
cessive in soil destroys roots, 
137; force causing to rise in 
stems, 62; insufficient, how 
affecting plants, 142; manur- 
ing increases capacity of soil 
for, 45; of plants almost 
wholly absorbed by root- 
hairs, 46; only youngest. roots 
absorb, 74; plants contain 
large amounts of, 57; root- 
hairs absorb, with force, 73; 
seeds absorb, by contact, 22. 



Index. 



303 



Water-sprouts on fruit trees. 
140. 

Water supply, unfavorable, the 
plant as affected by, 137. 

Watering, excessive, may pro- 
duce a dropsical condition, 
139; copious, at intervals 
preferable to frequent slight 
watering, 138; injudicious, 
138; of potted plants, 70; re- 
cently - transplanted plants, 
250. 

Weeds, 186; annual, biennial 
and perennial, 186; cause de- 
ficient light in low -growing 
crops, 148; how destroyed, 
63; plants as affected by, 186. 

Wet-bulb depression. 133. 

Whip -grafting, 224. 

White grubs, 163. 

White hellebore, 166, 



Whole-root grafts, 226. 

Wind breaks, 129. 

Wind, excessive, effect of, on 
plants, 150; insufficient, effect 
on the plant, 150; insufficient, 
promotes damage from frost, 
151; insufficient, promotes de- 
velopment of fungous para- 
sites, 150; tends to avert 
frost 134; unfavorable, how 
affecting the plant, 150. 

Wood ashes, 158. 

Woodchucks. dainage from, 161. 

Wood, darkening of, 124. 

Wood, maturity of, favored by 
a dry soil, 127; by pinching 
terminal buds, 128; indicated 
by leaf fall, 113. 

Wounds, healing of, 56; un- 
healed, introduce decay, 255. 



JAN 6 1906 



